Photoelectric conversion element and solid-state imaging device

ABSTRACT

A photoelectric conversion element according to an embodiment of the present disclosure includes: a first electrode; a second electrode disposed to be opposed to the first electrode; and an organic photoelectric conversion layer provided between the first electrode and the second electrode. The organic photoelectric conversion layer has a domain of one organic semiconductor material therein. The domain of the one organic semiconductor material has a percolation structure in which the domain vertically extends in the organic photoelectric conversion layer in a film-thickness direction, and has a smaller domain length in a plane direction of the organic photoelectric conversion layer than a domain length in the film-thickness direction of the organic photoelectric conversion layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/763,611, filed May 13, 2020, which is a national stage applicationunder 35 U.S.C. 371 and claims the benefit of PCT Application No.PCT/JP2018/042417 having an international filing date of 16 Nov. 2018,which designated the United States, which PCT application claimed thebenefit of Japanese Patent Application No. 2017-222977 filed 20 Nov.2017, the entire disclosures of each of which are incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates to a photoelectric conversion element anda solid-state imaging device including this.

BACKGROUND ART

In recent years, devices including organic thin films have beendeveloped. One of such devices is an organic photoelectric conversionelement. There has been proposed an organic thin-film solar cell, anorganic imaging element, or the like including the organic photoelectricconversion element. A bulk heterostructure is adopted in the organicphotoelectric conversion element to increase external quantumefficiency. In bulk heterostructure, a p-type organic semiconductor andan n-type organic semiconductor are mixed. However, the organicphotoelectric conversion element has a problem that it is not possibleto obtain sufficient external quantum efficiency due to a low conductivecharacteristic of an organic semiconductor. In addition, the organicimaging element has a problem that an electric output signal is easilydelayed with respect to incident light.

In general, it has been found that molecular orientation is importantfor conduction of an organic semiconductor. The same applies to anorganic photoelectric conversion element having a bulk heterostructure.For this reason, in an organic photoelectric conversion element in whicha conduction direction is perpendicular to a substrate, it is preferablethat the organic semiconductor be oriented parallel with the substrate.In contrast, for example, PTL 1 discloses a photoelectric conversionelement including an organic semiconductor compound having horizontalorientation. For example, PTL 2 discloses an organic thin-film solarcell in which an orientation control layer is provided in a lower layerof an i-layer. For example, PTL 3 discloses a method of manufacturing anorganic photoelectric conversion element that controls the orientationof a photoelectric conversion layer by controlling a substratetemperature to form a film.

CITATION LIST Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No. 2009-60053

PTL 2: Japanese Unexamined Patent Application Publication No. 2007-59457

PTL 3: Japanese Unexamined Patent Application Publication No.2008-258421

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

As described above, the photoelectric conversion element including anorganic semiconductor material is requested to increase the externalquantum efficiency and response speed.

It is desirable to provide a photoelectric conversion element and asolid-state imaging device that each make it possible to increaseexternal quantum efficiency and response speed.

A photoelectric conversion element according to an embodiment of thepresent disclosure includes: a first electrode; a second electrodedisposed to be opposed to the first electrode; and an organicphotoelectric conversion layer provided between the first electrode andthe second electrode. The organic photoelectric conversion layer has adomain of one organic semiconductor material therein. The domain of theone organic semiconductor material has a percolation structure in whichthe domain vertically extends in the organic photoelectric conversionlayer in a film-thickness direction, and has a smaller domain length ina plane direction of the organic photoelectric conversion layer than adomain length in the film-thickness direction of the organicphotoelectric conversion layer.

A solid-state imaging device according to an embodiment of the presentdisclosure includes pixels each including one or more organicphotoelectric conversion sections, and includes the above-describedphotoelectric conversion element according to the embodiment of thepresent disclosure as the organic photoelectric conversion section.

In each of the photoelectric conversion element according to theembodiment of the present disclosure and the solid-state imaging deviceaccording to the embodiment of the present disclosure, the organicphotoelectric conversion layer provided between the first electrode andthe second electrode includes the one organic semiconductor materialthat forms the domain having the predetermined shape in the layer. Thedomain of this one organic semiconductor material has the percolationstructure in which the domain vertically extends in the organicphotoelectric conversion layer in the film-thickness direction, and hasthe smaller domain length in the plane direction of the organicphotoelectric conversion layer than the domain length in thefilm-thickness direction. This makes it possible to appropriatelycontrol a mixture state of organic semiconductor materials included inthe organic photoelectric conversion layer.

The photoelectric conversion element according to the embodiment of thepresent disclosure and the solid-state imaging device according to theembodiment of the present disclosure each includes the one organicsemiconductor material that forms the domain as described above in thelayer, and the organic semiconductor materials included in the organicphotoelectric conversion layer are thus controlled in the appropriatemixture state. This makes it possible to increase the external quantumefficiency and response speed.

It is to be noted that the effects described here are not necessarilylimited, but any of effects described in the present disclosure may beincluded.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a schematic cross-sectional view of a configuration of aphotoelectric conversion element according to an embodiment of thepresent disclosure.

FIG. 2 is a schematic diagram illustrating an example of a mixture stateof respective organic semiconductor materials in an organicphotoelectric conversion layer illustrated in FIG. 1.

FIG. 3 is a TEM image for describing an interference fringe.

FIG. 4 is a schematic plan view of a configuration of a unit pixel ofthe photoelectric conversion element illustrated in FIG. 1.

FIG. 5 is a schematic cross-sectional view for describing a method ofmanufacturing the photoelectric conversion element illustrated in FIG.1.

FIG. 6 is a schematic cross-sectional view illustrating a processfollowing FIG. 5.

FIG. 7 is a schematic cross-sectional view of a configuration of aphotoelectric conversion element according to a modification example ofthe present disclosure.

FIG. 8 is a block diagram illustrating an overall configuration of asolid-state imaging element including the photoelectric conversionelement illustrated in FIG. 1.

FIG. 9 is a functional block diagram illustrating an example of asolid-state imaging device (camera) including the solid-state imagingelement illustrated in FIG. 8.

FIG. 10 is a block diagram depicting an example of a schematicconfiguration of an in-vivo information acquisition system.

FIG. 11 is a view depicting an example of a schematic configuration ofan endoscopic surgery system.

FIG. 12 is a block diagram depicting an example of a functionalconfiguration of a camera head and a camera control unit (CCU).

FIG. 13 is a block diagram depicting an example of schematicconfiguration of a vehicle control system.

FIG. 14 is a diagram of assistance in explaining an example ofinstallation positions of an outside-vehicle information detectingsection and an imaging section.

FIG. 15 is a diagram illustrating a TEM image (A) of Experiment Example1 and signal intensity (B) thereof.

FIG. 16 includes TEM images of Experiment Examples 1 and 4.

FIG. 17 includes TEM images of Experiment Examples 6 and 8.

MODES FOR CARRYING OUT THE INVENTION

The following describes embodiments of the present disclosure in detailwith reference to the drawings. The following description is a specificexample of the present disclosure, but the present disclosure is notlimited to the following embodiment. In addition, the present disclosuredoes not limit the disposition, dimensions, dimension ratios, and thelike of respective components illustrated in the diagrams thereto. It isto be noted that description is given in the following order.

1. Embodiment (A photoelectric conversion element in which an organicphotoelectric conversion layer includes one organic semiconductormaterial that forms a domain having a predetermined shape)

1-1. Configuration of Photoelectric Conversion Element 1-2. Method ofManufacturing Photoelectric Conversion Element 1-3. Workings and Effects

2. Modification Example (A photoelectric conversion element in which aplurality of organic photoelectric conversion sections is stacked)

3. Application Examples 4. Working Examples 1. Embodiment

FIG. 1 illustrates a cross-sectional configuration of a photoelectricconversion element (photoelectric conversion element 10) according to anembodiment of the present disclosure. The photoelectric conversionelement 10 is included, for example, in one pixel (unit pixel P) in asolid-state imaging device (solid-state imaging device 1) such as abackside illumination type (backside light receiving type) CCD (ChargeCoupled Device) image sensor or CMOS (Complementary Metal OxideSemiconductor) image sensor (see FIG. 8). The photoelectric conversionelement 10 is of a so-called vertical spectroscopic type in which oneorganic photoelectric conversion section 11G, and two inorganicphotoelectric conversion sections 11B and 11R are stacked in a verticaldirection. The organic photoelectric conversion section 11G, and the twoinorganic photoelectric conversion sections 11B and 11R each selectivelydetect respective pieces of light in different wavelength regions toperform photoelectric conversion. In the present embodiment, an organicphotoelectric conversion layer 16 included in the organic photoelectricconversion section 11G has a configuration in which the organicphotoelectric conversion layer 16 is formed by using an organicsemiconductor material (one organic semiconductor material). The organicsemiconductor material (one organic semiconductor material) forms adomain having a predetermined shape in the layer.

(1-1. Configuration of Photoelectric Conversion Element)

In the photoelectric conversion element 10, one organic photoelectricconversion section 11G, and two inorganic photoelectric conversionsections 11B and 11R are stacked in the vertical direction for each unitpixel P. The organic photoelectric conversion section 11G is provided ona rear surface (first surface 11S1) side of a semiconductor substrate11. The inorganic photoelectric conversion sections 11B and 11R areembedded and formed in the semiconductor substrate 11, and stacked inthe thickness direction of the semiconductor substrate 11. The organicphotoelectric conversion section 11G includes the organic photoelectricconversion layer 16 including a p-type semiconductor and an n-typesemiconductor and having a bulk hetero junction structure in a layer.The bulk hetero junction structure is a p/n junction surface formed bymixture of a p-type semiconductor and an n-type semiconductor.

The organic photoelectric conversion section 11G and the inorganicphotoelectric conversion sections 11B and 11R perform photoelectricconversion by selectively detecting respective pieces of light ofdifferent wavelengths. Specifically, the organic photoelectricconversion section 11G acquires a green (G) color signal. The inorganicphotoelectric conversion sections 11B and 11R respectively acquire ablue (B) color signal and a red (R) color signal by using a differencein absorption coefficients. This enables the photoelectric conversionelement 10 to acquire a plurality types of color signals in one pixelwithout using a color filter.

It is to be noted that, in the present embodiment, description is givenof a case of reading an electron as a signal charge (case where then-type semiconductor region is used as a photoelectric conversion layer)of a pair of the electron and hole generated from photoelectricconversion. In addition, in the drawings, “+(plus)” assigned to “p” and“n” indicates that the concentration of p-type or n-type impurities ishigh, and “++” indicates that the concentration of p-type or n-typeimpurities is further higher than “+”.

The semiconductor substrate 11 includes, for example, an n-type silicon(Si) substrate, and has a p-well 61 in a predetermined region. A secondsurface (front surface of the semiconductor substrate 11) 1152 of thep-well 61 is provided with, for example, various floating diffusions(floating diffusion layers) FD (e.g., FD1, FD2, and FD3), varioustransistors Tr (e.g., vertical transistor (transfer transistor) Tr1,transfer transistor Tr2, amplifier transistor (modulation element) AMP,and reset transistor RST), and a multilayer wiring line 70. Themultilayer wiring line 70 has a configuration in which wiring layers 71,72, and 73, for example, are stacked in an insulating layer 74. Inaddition, a peripheral portion of the semiconductor substrate 11 isprovided with a peripheral circuit (not illustrated) including a logiccircuit or the like.

It is to be noted that FIG. 1 illustrates the first surface 11S1 side ofthe semiconductor substrate 11 as a light incident surface S1, and thesecond surface 11S2 side thereof as a wiring layer side S2.

The inorganic photoelectric conversion sections 11B and 11R eachinclude, for example, a PIN (Positive Intrinsic Negative) typephotodiode, and each have a p-n junction in a predetermined region ofthe semiconductor substrate 11. The inorganic photoelectric conversionsections 11B and 11R enable light to be dispersed in the verticaldirection by using the wavelength bands of absorbed light that aredifferent in accordance with the incidence depth on the siliconsubstrate.

The inorganic photoelectric conversion section 11B selectively detectsthe blue light to accumulate the signal charge corresponding to blue,and is installed at a depth that allows the blue light to bephotoelectrically converted efficiently. The inorganic photoelectricconversion section 11R selectively detects the red light to accumulatethe signal charge corresponding to red, and is installed at a depth thatallows the red light to be photoelectrically converted efficiently. Itis to be noted that blue (B) is a color corresponding to a wavelengthband of 450 nm to 495 nm, for example, and red (R) is a colorcorresponding to a wavelength band of 620 nm to 750 nm, for example. Itis sufficient if the inorganic photoelectric conversion sections 11B and11R are able to detect pieces of light of a portion or all of therespective wavelength bands.

Specifically, as illustrated in FIG. 1, the inorganic photoelectricconversion section 11B and the inorganic photoelectric conversionsection 11R each include, for example, a p+ region serving as a holeaccumulation layer and an n region serving as an electron accumulationlayer (they each have a p-n-p stacked structure). The n region of theinorganic photoelectric conversion section 11B is coupled to thevertical transistor Tr1. The p+ region of the inorganic photoelectricconversion section 11B bends along the vertical transistor Tr1, andlinks to the p+ region of the inorganic photoelectric conversion section11R.

As described above, the second surface 11S2 of the semiconductorsubstrate 11 is provided with, for example, the floating diffusions(floating diffusion layers) FD1, FD2, and FD3, the vertical transistor(transfer transistor) Tr1, the transfer transistor Tr2, the amplifiertransistor (modulation element) AMP, and the reset transistor RST.

The vertical transistor Tr is a transfer transistor that transfers, tothe floating diffusion FD1, the signal charges (electrons, here)generated and accumulated in the inorganic photoelectric conversionsection 11B. The signal charges correspond to blue. The inorganicphotoelectric conversion section 11B is formed at a deep position fromthe second surface 11S2 of the semiconductor substrate 11, and thus itis preferable that the transfer transistor of the inorganicphotoelectric conversion section 11B include the vertical transistorTr1.

The transfer transistor Tr2 transfers, to the floating diffusion FD2,the signal charges (electrons, here) generated and accumulated in theinorganic photoelectric conversion section 11R. The signal chargescorrespond to red. The transfer transistor Tr2 includes, for example, aMOS transistor.

The amplifier transistor AMP is a modulation element that modulates,into a voltage, an amount of the charges generated in the organicphotoelectric conversion section 11G, and includes, for example, a MOStransistor.

The reset transistor RST resets the charges transferred from the organicphotoelectric conversion section 11G to the floating diffusion FD3, andincludes, for example, a MOS transistor.

A lower first contact 75, a lower second contact 76, and an uppercontact 13B each include, for example, a doped silicon material such asPDAS (Phosphorus Doped Amorphous Silicon), or a metallic material suchas aluminum (Al), tungsten (W), titanium (Ti), cobalt (Co), hafnium(Hf), or tantalum (Ta).

The organic photoelectric conversion section 11G is provided on thefirst surface 11S1 side of the semiconductor substrate 11. The organicphotoelectric conversion section 11G has a configuration in which, forexample, a lower electrode 15, the organic photoelectric conversionlayer 16, and an upper electrode 17 are stacked in this order from theside of the first surface 11S1 of the semiconductor substrate 11. Thelower electrode 15 is, for example, separately formed for eachphotoelectric conversion element 10. The organic photoelectricconversion layer 16 and the upper electrode 17 are provided assuccessive layers common to the plurality of photoelectric conversionelements 10. The organic photoelectric conversion section 11G is anorganic photoelectric conversion element that absorbs the green lightcorresponding to a portion or all of selective wavelength bands (e.g.,450 nm or more and 650 nm or less) to generate an electron-hole pair.

Between the first surface 1151 of the semiconductor substrate 11 and thelower electrode 15, for example, inter-layer insulating layers 12 and 14are stacked in this order from the semiconductor substrate 11 side. Theinter-layer insulating layers each have a configuration in which, forexample, a layer (fixed charge layer) 12A having a fixed charge and adielectric layer 12B having insulation properties are stacked. Aprotective layer 18 is provided on the upper electrode 17. An on-chiplens layer 19 included in an on-chip lens 19L and also serving as aplanarization layer is disposed above the protective layer 18.

A through-electrode 63 is provided between the first surface 11S1 andthe second surface 1152 of the semiconductor substrate 11. The organicphotoelectric conversion section 11G is coupled to a gate Gamp of theamplifier transistor AMP and the floating diffusion FD3 via thisthrough-electrode 63. This enables the photoelectric conversion element10 to transfer charges generated in the organic photoelectric conversionsection 11G on the first surface 1151 side of the semiconductorsubstrate 11 to the second surface 11S2 side of the semiconductorsubstrate 11 via the through-electrode 63 in a favorable manner, thusmaking it possible to improve characteristics.

The through-electrode 63 is provided, for example, for each organicphotoelectric conversion section 11G of the photoelectric conversionelement 10. The through-electrode 63 has a function of a connector forthe organic photoelectric conversion section 11G and the gate Gamp ofthe amplifier transistor AMP, and the floating diffusion FD3, and servesas a transmission path for the charges generated in the organicphotoelectric conversion section 11G.

The lower end of the through-electrode 63 is coupled to a coupledportion 71A in the wiring layer 71, for example, and the coupled portion71A and the gate Gamp of the amplifier transistor AMP are coupled viathe lower first contact 75. The coupled portion 71 and the floatingdiffusion FD3 are coupled to the lower electrode 15 via the lower secondcontact 76. It is to be noted that FIG. 1 illustrates thethrough-electrode 63 in the shape of a cylinder, but this is notlimitative. The through-electrode 63 may have a tapered shape, forexample.

As illustrated in FIG. 1, a reset gate Grst of the reset transistor RSTis preferably disposed next to the floating diffusion FD3. This makes itpossible to cause the reset transistor RST to reset the chargesaccumulated in the floating diffusion FD3.

In the photoelectric conversion element 10 according to the presentembodiment, light inputted to the organic photoelectric conversionsection 11G from the upper electrode 17 side is absorbed by the organicphotoelectric conversion layer 16. Excitons thus generated move to aninterface between an electron donor and an electron acceptor included inthe organic photoelectric conversion layer 16, and undergo excitonseparation, that is, dissociate into electrons and holes. The charges(electrons and holes) generated here are transported to differentelectrodes by diffusion due to a difference in carrier concentration orby an internal electric field due to a difference in work functionsbetween an anode (here, the upper electrode 17) and a cathode (here, thelower electrode 15), and are detected as a photocurrent. In addition,the application of an electric potential between the lower electrode 15and the upper electrode 17 makes it possible to control directions inwhich electrons and holes are transported.

The following describes configurations, materials, or the like ofrespective sections.

The organic photoelectric conversion section 11G is an organicphotoelectric conversion element that absorbs the green lightcorresponding to a portion or all of selective wavelength bands (e.g.,450 nm or more and 650 nm or less) to generate an electron-hole pair.

The lower electrode 15 is provided in a region that directly faceslight-receiving surfaces of the inorganic photoelectric conversionsections 11B and 11R formed in the semiconductor substrate 11 and coversthese light-receiving surfaces. The lower electrode 15 includes anelectrically-conducive layer having light-transmissivity, and includes,for example, ITO (indium-tin oxide). However, as a material included inthe lower electrode 15, a tin oxide (SnO₂)-based material obtained byadding a dopant or a zinc oxide-based material formed by adding a dopantto zinc oxide (ZnO) may be used in addition to this ITO. Examples of thezinc oxide-based materials include aluminum zinc oxide (AZO) obtained byadding aluminum (Al) as the dopant, gallium (Ga)-added gallium zincoxide (GZO), and indium (In)-added indium zinc oxide (IZO). In additionto these, CuI, InSbO₄, ZnMgO, CuInO₂, MglN₂O₄, CdO, ZnSnO₃, or the likemay also be used.

The organic photoelectric conversion layer 16 converts optical energyinto electric energy. The organic photoelectric conversion layer 16includes, for example, two or more types of organic semiconductormaterials, and preferably includes, for example, one or both of a p-typesemiconductor and an n-type semiconductor. For example, in a case wherethe organic photoelectric conversion layer 16 includes the two types oforganic semiconductor materials including a p-type semiconductor and ann-type semiconductor, for example, one of the p-type semiconductor andthe n-type semiconductor is preferably a material having transmissivityto visible light, and the other thereof is preferably a material thatphotoelectrically converts light in a selective wavelength region (e.g.,450 nm or more and 650 nm or less). Alternatively, the organicphotoelectric conversion layer 16 preferably includes three types oforganic semiconductor materials including a material (light absorber),an n-type semiconductor, and a p-type semiconductor. The material (lightabsorber) photoelectrically converts light in a selective wavelengthregion. The n-type semiconductor and the p-type semiconductor each havelight-transmissivity to visible light. The organic photoelectricconversion layer 16 has a bulk heterostructure in which the plurality ofthese organic semiconductor materials is randomly mixed in the layer.

FIG. 2 schematically illustrates an example of a mixture state of therespective organic semiconductor materials in the organic photoelectricconversion layer 16 according to the present embodiment. In the organicphotoelectric conversion layer 16, as illustrated in FIG. 2, forexample, the above-described three types of organic semiconductormaterials (light absorber, p-type semiconductor, and n-typesemiconductor) are randomly mixed. In the organic photoelectricconversion layer 16, the respective organic semiconductor materials formgrains (e.g., a grain Gc of the light absorber and a grain Gn of then-type semiconductor). In the present embodiment, there is a domain(e.g., domain Dp) of at least one (e.g., p-type semiconductor (oneorganic semiconductor material)) of a plurality of types of organicsemiconductor materials in the layer. It is to be noted that the domainis, for example, a region including a continuous arrangement of oneorganic semiconductor material. In addition, in the organicphotoelectric conversion layer 16, a domain (e.g., n-type semiconductoror light absorber) may be formed in addition to the domain of a p-typesemiconductor. In addition, a domain may include two or more types oforganic semiconductor materials.

The domain Dp of the p-type semiconductor according to the presentembodiment preferably has a percolation structure in which the domain Dpvertically extends in the organic photoelectric conversion layer 16 inthe film-thickness direction (Y-axis direction). Further, the domain Dpof the p-type semiconductor preferably has a shape in which the length(domain length) of the domain in the plane direction (e.g., X-axisdirection) is smaller than the domain length in the film-thicknessdirection. That is, the p-type semiconductor preferably forms the domainDp extending in the p film-thickness direction of the organicphotoelectric conversion layer 16.

FIG. 3 is an enlarged view of a portion of an image (TEM image) obtainedby photographing the organic photoelectric conversion layer 16(Experiment Example 1 described below) by a transmission electronmicroscope under a defocus condition. The organic photoelectricconversion layer 16 is fabricated by using a p-type semiconductor thatforms the domain as described above. In the organic photoelectricconversion layer 16 according to the present embodiment, an interferencefringe including two or more lines as illustrated by dotted lines inFIG. 3 is confirmed in the region corresponding to the domain Dp. Aninterference fringe preferably includes less than ten lines.

This interference fringe is observed because the period of p-typesemiconductor molecules forming a domain in the major axis direction andelectronic waves cause phase contrast. That is, paired lines that areadjacent to each other among the two or more lines included in theinterference fringe each correspond to the molecular period of p-typesemiconductor molecules in the major axis direction. The interferencefringe extends in the organic photoelectric conversion layer 16substantially in the film-thickness direction, and preferably has alength of 20 nm or more. In addition, as the extending direction of theinterference fringe, specifically, the angle formed between theinterference fringe and the electrode surface of the lower electrode 15is preferably more than 450 and 900 or less. The interval between thesetwo lines preferably falls within ±50% of the molecular length of thep-type semiconductor, for example. More preferably, the interval betweenthese two lines falls within +30%. That is, p-type semiconductors areperiodically stacked in the same direction between the two linesincluded in the interference fringe. It is to be noted that themolecular length of a p-type semiconductor is the length of themolecules of the p-type semiconductor in the major axis direction.

As described above, the organic photoelectric conversion layer 16preferably includes two types of organic semiconductor materialsincluding an n-type semiconductor and a p-type semiconductor or threetypes of organic semiconductor materials including a light absorber, ann-type semiconductor, and a p-type semiconductor. There is a junctionsurface (p/n junction surface) between the p-type semiconductor and then-type semiconductor in the layer. The light absorber has the maximalabsorption wavelength within a range of, for example, 450 nm or more and650 nm or less. The p-type semiconductor relatively functions as anelectron donor (donor), and the use of a material having a holetransporting property is preferable, for example. The n-typesemiconductor relatively functions as an electron acceptor (acceptor),and the use of a material having an electron transporting property ispreferable, for example. The organic photoelectric conversion layer 16provides a field in which excitons generated at the time of lightabsorption are separated into electrons and holes, and specifically,excitons are separated into electrons and holes on the interface (p/njunction surface) between the electron donor and the electron acceptor.The thickness of the organic photoelectric conversion layer 16 is, forexample, 50 nm to 500 nm. The interface between the organicphotoelectric conversion layer 16 and the upper electrode 17 preferablyhas a surface roughness of 10 nm or less.

It is to be noted that an example in which a p-type semiconductor formsthe domain Dp has been described in the present embodiment, but this isnot limitative. For example, an n-type semiconductors may form a domain.

The upper electrode 17 includes an electrically-conductive film havinglight-transmissivity similar to that of the lower electrode 15. In thesolid-state imaging device 1 including the photoelectric conversionelement 10 as one pixel, this upper electrode 17 may be separated foreach pixel, or may be formed as an electrode common to each pixel. Thethickness of the upper electrode 17 is, for example, 10 nm to 200 nm.

It is to be noted that other layers may be provided between the organicphotoelectric conversion layer 16 and the lower electrode 15 and betweenthe organic photoelectric conversion layer 16 and the upper electrode17. Specifically, for example, an underlying film, a hole transportlayer, an electron blocking film, the organic photoelectric conversionlayer 16, a hole blocking film, a buffer film, an electron transportlayer, a work function adjusting film, and the like may be stacked inorder from the lower electrode 15 side.

The fixed charge layer 12A may be a film having a positive fixed chargeor a film having a negative fixed charge. As materials of the filmhaving the negative fixed charge, hafnium oxide, aluminum oxide,zirconium oxide, tantalum oxide, titanium oxide, and the like areincluded. In addition, as a material other than the above-describedmaterials, lanthanum oxide, praseodymium oxide, cerium oxide, neodymiumoxide, promethium oxide, samarium oxide, europium oxide, gadoliniumoxide, terbium oxide, dysprosium oxide, holemium oxide, thulium oxide,ytterbium oxide, lutetium oxide, yttrium oxide, an aluminum nitridefilm, a hafnium oxynitride film, an aluminum oxynitride film, or thelike may be used.

The fixed charge layer 12A may also have a configuration in which two ormore types of films are stacked. This makes it possible to furtherimprove a function of a hole accumulation layer in a case of a filmhaving the negative fixed charge, for example.

Although materials of the dielectric layer 12B are not limited inparticular, the dielectric layer 12B includes a silicon oxide film,TEOS, a silicon nitride film, a silicon oxynitride film, or the like,for example.

The inter-layer insulating layer 14 includes, for example, asingle-layer film including one type of silicon oxide, silicon nitride,silicon oxynitride (SiON), and the like, or a stacked film including twoor more types thereof.

The protective layer 18 includes a material having light-transmissivity,and includes, for example, a single layer film including any of siliconoxide, silicon nitride, silicon oxynitride, and the like, or a stackedfilm including two or more types thereof. The thickness of theprotective layer 18 is, for example, 100 nm to 30000 nm.

The on-chip lens layer 19 is formed on the protective layer 18 to coverthe entire surface thereof. The plurality of on-chip lenses(microlenses) 19L is provided on the front surface of the on-chip lenslayer 19. The on-chip lenses 19L each condense light inputted from abovethe on-chip lens 19L on the respective light-receiving surfaces of theorganic photoelectric conversion section 11G and the inorganicphotoelectric conversion sections 11B and 11R. In the presentembodiment, the multilayer wiring line 70 is formed on the secondsurface 11S2 side of the semiconductor substrate 11. This enables therespective light-receiving surfaces of the organic photoelectricconversion section 11G and the inorganic photoelectric conversionsections 11B and 11R to be disposed close to each other, thus making itpossible to reduce sensitivity variations between the respective colorsgenerated depending on an F-value of the on-chip lens 19L.

FIG. 4 is a plan view of an configuration example of a photoelectricconversion element including a pixel in which a plurality ofphotoelectric conversion sections (e.g., the above-described inorganicphotoelectric conversion sections 11B and 11R, and organic photoelectricconversion section 11G) to which the technology according to the presentdisclosure is applicable are stacked. That is, FIG. 4 illustrates anexample of a planar configuration of the unit pixel P included in apixel section 1 a illustrated in FIG. 8, for example.

The unit pixel P includes a photoelectric conversion region 1100 inwhich a red photoelectric conversion section (inorganic photoelectricconversion section 11R in FIG. 1), a blue photoelectric conversionsection (inorganic photoelectric conversion section 11B in FIG. 3), anda green photoelectric conversion section (organic photoelectricconversion section 11G in FIG. 1) (neither of which is illustrated inFIG. 4) that photoelectrically convert respective pieces of light of thewavelengths of R (Red), G (Green), and B (Blue) are stacked in threelayers in the order of the green photoelectric conversion section, theblue photoelectric conversion section, and the red photoelectricconversion section, for example, from the light-receiving surface (lightincident surface S1 in FIG. 1) side. Further, the unit pixel P includesa Tr group 1110, a Tr group 1120, and a Tr group 1130 as charge readoutsections that read charges corresponding to the respective pieces oflight of wavelengths of R, G, and B from the red photoelectricconversion section, the green photoelectric conversion section, and theblue photoelectric conversion section. The solid-state imaging device 1disperses light in the vertical direction in one unit pixel P, that is,disperses the respective pieces of light of R, G, and B in therespective layers serving as the red photoelectric conversion section,the green photoelectric conversion section, and the blue photoelectricconversion section stacked in the photoelectric conversion region 1100.

The Tr group 1110, the Tr group 1120, and the Tr group 1130 are formedon the periphery of the photoelectric conversion region 1100. The Trgroup 1110 outputs, as a pixel signal, a signal charge corresponding tothe light of R generated and accumulated in the red photoelectricconversion section. The Tr group 1110 includes a transfer Tr (MOS FET)1111, a reset Tr 1112, an amplification Tr 1113, and a selection Tr1114. The Tr group 1120 outputs, as a pixel signal, a signal chargecorresponding to the light of B generated and accumulated in the bluephotoelectric conversion section. The Tr group 1120 includes a transferTr 1121, a reset Tr 1122, an amplification Tr 1123, and a selection Tr1124. The Tr group 1130 outputs, as a pixel signal, a signal chargecorresponding to the light of G generated and accumulated in the greenphotoelectric conversion section. The Tr group 1130 includes a transferTr 1131, a reset Tr 1132, an amplification Tr 1133, and a selection Tr1134.

The transfer Tr 1111 includes (source/drain region serving as) a gate G,a source/drain region S/D, and FD (floating diffusion) 1115. Thetransfer Tr 1121 includes a gate G, a source/drain region S/D, and FD1125. The transfer Tr 1131 includes a gate G, (source/drain region S/Dcoupled to) the green photoelectric conversion section of thephotoelectric conversion region 1100, and FD 1135. It is to be notedthat the source/drain region of the transfer Tr 1111 is coupled to thered photoelectric conversion section of the photoelectric conversionregion 1100, and the source/drain region S/D of the transfer Tr 1121 iscoupled to the blue photoelectric conversion section of thephotoelectric conversion region 1100.

The reset Trs 1112, 1132, and 1122, the amplification Trs 1113, 1133,and 1123, and the selection Trs 1114, 1134, and 1124 each include a gateG and a pair of source/drain regions S/D disposed across the gate G.

The FDs 1115, 1135, and 1125 are coupled to the respective source/drainregions S/D serving as sources of the reset Trs 1112, 1132, and 1122,and are coupled to the respective gates G of the amplification Trs 1113,1133 and 1123. A power supply Vdd is coupled to the common source/drainregion S/D in each of the reset Tr 1112 and the amplification Tr 1113,the reset Tr 1132 and the amplification Tr 1133, and the reset Tr 1122and the amplification Tr 1123. VSL (vertical signal line) is coupled toeach of the source/drain regions S/D serving as the respective sourcesof the selection Trs 1114, 1134, and 1124.

The technology according to the present disclosure is applicable to thephotoelectric conversion element as described above.

(1-2. Method of Manufacturing Photoelectric Conversion Element)

It is possible to manufacture the photoelectric conversion element 10according to the present embodiment, for example, in the followingmanner.

FIGS. 5 and 6 each illustrate a method of manufacturing thephotoelectric conversion element 10 in order of processes. First, asillustrated in FIG. 5, the p-well 61, for example, is formed as a firstelectrically-conductive well in the semiconductor substrate 11. Thesecond electrically-conductive (e.g., n-type) inorganic photoelectricconversion sections 11B and 11R are formed in this p-well 61. A p+region is formed in the vicinity of the first surface 11S1 of thesemiconductor substrate 11.

As also illustrated in FIG. 5, on the second surface 11S2 of thesemiconductor substrate 11, after n+ regions serving as the floatingdiffusions FD1 to FD3 are formed, a gate insulating layer 62 and a gatewiring layer 64 including the respective gates of the verticaltransistor Tr1, the transfer transistor Tr2, the amplifier transistorAMP, and the reset transistor RST are formed. This forms the verticaltransistor Tr1, the transfer transistor Tr2, the amplifier transistorAMP, and the reset transistor RST. Further, the multilayer wiring line70 is formed on the second surface 11S2 of the semiconductor substrate11. The multilayer wiring line 70 includes wiring layers 71 to 73 andthe insulating layer 74. The wiring layers 71 to 73 include the lowerfirst contact 75, the lower second contact 76, and the coupled portion71A.

As a base of the semiconductor substrate 11, for example, an SOI(Silicon on Insulator) substrate is used in which the semiconductorsubstrate 11, an embedded oxide film (not illustrated), and a holdingsubstrate (not illustrated) are stacked. Although not illustrated inFIG. 5, the embedded oxide film and the holding substrate are joined tothe first substrate surface 11S1 of the semiconductor substrate 11.After ion implantation, an annealing process is performed.

Then, a support substrate (not illustrated), another semiconductorsubstrate, or the like is joined to the second surface 11S2 side(multilayer wiring line 70 side) of the semiconductor substrate 11 andflipped vertically. Subsequently, the semiconductor substrate 11 isseparated from the embedded oxide film and the holding substrate of theSOI substrate to expose the first surface 11S1 of the semiconductorsubstrate 11. It is possible to perform these processes with technologyused in a normal CMOS process such as ion implantation and CVD (ChemicalVapor Deposition).

Then, as illustrated in FIG. 6, the semiconductor substrate 11 isprocessed from the first surface 11S1 side with dry etching, forexample, to form an annular opening 63H. The opening 63H has a depthpenetrating from the first surface 11S1 to the second surface 11S2 ofthe semiconductor substrate 11 as illustrated in FIG. 6, and reachingthe coupled portion 71A, for example.

Subsequently, as illustrated in FIG. 6, for example, the negative fixedcharge layer 12A is formed on the first surface 11S1 of thesemiconductor substrate 11 and a side face of the opening 63H. Two ormore types of films may be stacked as the negative fixed charge layer12A. This makes it possible to further improve the function of the holeaccumulation layer. The dielectric layer 12B is formed after thenegative fixed charge layer 12A is formed.

Next, an electric conductor is embedded in the opening 63H to form thethrough-electrode 63. As the electric conductor, for example, a metallicmaterial such as aluminum (Al), tungsten (W), titanium (Ti), cobalt(Co), hafnium (Hf), and tantalum (Ta) is usable in addition to a dopedsilicon material such as PDAS (Phosphorus Doped Amorphous Silicon).

Subsequently, after a pad section 13A is formed on the through-electrode63, the interlayer insulating layer 14 is formed on the dielectric layer12B and the pad section 13. In the interlayer insulating layer 14, theupper contact 13B and a pad section 13C are provided on the pad section13A. The upper contact 13B and the pad section 13C electrically couplethe lower electrode 15 and the through-electrode 63 (specifically, thepad section 13A on the through-electrode 63).

Next, the lower electrode 15, the organic photoelectric conversion layer16, the upper electrode 17, and the protective layer 18 are formed inthis order on the interlayer insulating layer 14. As the organicphotoelectric conversion layer 16, for example, films of theabove-described three types of organic semiconductor materials areformed by using, for example, a vacuum deposition method. Finally, theon-chip lens layer 19 is disposed that includes the plurality of on-chiplenses 19L on the surface thereof. Thus, the photoelectric conversionelement 10 illustrated in FIG. 1 is completed.

It is to be noted that, in a case where another organic layer (e.g.,electron-blocking layer, etc.) is formed on or under the organicphotoelectric conversion layer 16 as described above, it is desirable tocontinuously form the other organic layer (by a vacuum-consistentprocess) in a vacuum process. In addition, the method of forming theorganic photoelectric conversion layer 16 is not necessarily limited tothe method using a vacuum deposition method, but another method, forexample, a spin-coating technique, a printing technique, or the like maybe used.

When light enters the organic photoelectric conversion section 11G viathe on-chip lens 19L in the photoelectric conversion element 10, thelight passes through the organic photoelectric conversion section 11G,the inorganic photoelectric conversion sections 11B and the 11R in thisorder, and the respective pieces of light of green, blue, and red arephotoelectrically converted in the passing process. The followingdescribes an operation of acquiring signals of the respective colors.

(Acquisition of Green Color Signal by Organic Photoelectric ConversionSection 11G)

First, the green light of the pieces of light inputted into thephotoelectric conversion element 10 is selectively detected (absorbed)and photoelectrically converted by the organic photoelectric conversionsection 11G.

The organic photoelectric conversion section 11G is coupled to a gateGamp of the amplifier transistor AMP and the floating diffusion FD3 viathe through-electrode 63. Thus, the electron of the electron-hole pairgenerated in the organic photoelectric conversion section 11G is takenout from the lower electrode 15 side, transferred to the second surface11S2 side of the semiconductor substrate 11 via the through-electrode63, and accumulated in the floating diffusion FD3. At the same time asthis, the amplifier transistor AMP modulates the amount of the chargesgenerated in the organic photoelectric conversion section 11G into avoltage.

In addition, the reset gate Grst of the reset transistor RST is disposednext to the floating diffusion FD3. This causes the reset transistor RSTto reset the charges accumulated in the floating diffusion FD3.

Here, the organic photoelectric conversion section 11G is coupled to notonly the amplifier transistor AMP, but also the floating diffusion FD3via the through-electrode 63, making it possible for the resettransistor RST to easily reset the charges accumulated in the floatingdiffusion FD3.

In contrast, in a case where the through-electrode 63 and the floatingdiffusion FD3 are not coupled, it is difficult to reset the chargesaccumulated in the floating diffusion FD3, resulting in application of alarge voltage to pull out the charges to the upper electrode 17 side.Accordingly, there is a possibility that the organic photoelectricconversion layer 16 is damaged. In addition, a structure that enablesresetting in a short period of time leads to increased dark-time noiseand results in a trade-off. This structure is thus difficult.

(Acquisition of Blue Color Signal and Red Color Signal by InorganicPhotoelectric Conversion Sections 11B and 11R)

Subsequently, the blue light and the red light of the pieces of lightpassing through the organic photoelectric conversion section 11G arerespectively absorbed in sequence and photoelectrically converted in theinorganic photoelectric conversion section 11B and the inorganicphotoelectric conversion section 11R. In the inorganic photoelectricconversion section 11B, electrons corresponding to the inputted bluelight are accumulated in the n-region of the inorganic photoelectricconversion section 11, and the accumulated electrons are transferred tothe floating diffusion FD1 by the vertical transistor Tr1. Similarly, inthe inorganic photoelectric conversion section 11R, electronscorresponding to the inputted red light are accumulated in the n-regionof the inorganic photoelectric conversion section 11R, and theaccumulated electrons are transferred to the floating diffusion FD2 bythe transfer transistor Tr2.

(1-3. Workings and Effects)

As described above, an organic photoelectric conversion element used foran organic thin-film solar cell, an organic imaging element, or the likeadopts a bulk heterostructure in which a p-type organic semiconductorand an n-type organic semiconductor are mixed. However, organicsemiconductors have low conductive characteristics, and the organicphotoelectric conversion element is thus unable to obtain sufficientquantum efficiency. Therefore, there is a problem that an electricoutput signal is easily delayed with respect to the incident light.

In general, it is found that molecular orientation is important forconduction of organic semiconductors. The same applies to an organicphotoelectric conversion element having a bulk heterostructure. It isknown that, in an organic photoelectric conversion element in which aconduction direction is perpendicular to a substrate, it is generallypreferable that the organic semiconductor be oriented parallel with thesubstrate. Therefore, as described above, various measures are taken toimprove the horizontal orientation of an organic semiconductor includedin an organic photoelectric conversion layer.

However, simply orienting the organic molecules parallel with thesubstrate does not sufficiently increase the conductive characteristicof the organic photoelectric conversion element, failing in sufficientimprovement in the quantum efficiency and responsiveness in some cases.In a photoelectric conversion element having a bulk heterostructure,each material included in the bulk heterostructure in the layer isrequested to form an appropriate grain. For example, in a case where alarge defect is present on the grain boundary, the conductivecharacteristic is greatly degraded. One reason for this is that chargeis trapped at a trap level of the defect or the defect serves as anenergy barrier to inhibit charge transfer between grains when the chargeconducts on the grain boundary. This is considered to lead todeterioration in quantum efficiency and response speed.

In contrast, in the present embodiment, the organic photoelectricconversion layer 16 includes an organic semiconductor material (oneorganic semiconductor material) that forms a domain (e.g., domain Dp)having a predetermined shape in the layer. Specifically, the organicphotoelectric conversion layer 16 is formed that includes an organicsemiconductor material which forms a domain having a percolationstructure and having a shape in which the length of the domain in theplane direction is smaller than the length of the domain in thefilm-thickness direction. In the percolation structure, the domainvertically extends in the organic photoelectric conversion layer 16 inthe film-thickness direction. This makes it possible to appropriatelycontrol a mixture state of organic semiconductor materials in theorganic photoelectric conversion layer.

As described above, the photoelectric conversion element 10 according tothe present embodiment includes one organic semiconductor material(e.g., p-type semiconductor) in the organic photoelectric conversionlayer 16. The one organic semiconductor material (e.g., p-typesemiconductor) forms the domain as described above in the organicphotoelectric conversion layer 16. This causes organic semiconductormaterials (e.g., an n-type semiconductor and a light absorber inaddition to the above-described p-type semiconductor) included in theorganic photoelectric conversion layer 16 to be controlled in anappropriate mixture state. This makes it possible to increase theexternal quantum efficiency and response speed.

Next, a modification example of the present disclosure is described. Itis to be noted that components corresponding to those of thephotoelectric conversion element 10 according to the above-describedembodiment are denoted by the same reference numerals, and descriptionthereof is omitted.

2. Modification Example

FIG. 7 illustrates a cross-sectional configuration of a photoelectricconversion element (photoelectric conversion element 20) according to amodification example of the present disclosure. The photoelectricconversion element 20 is included, for example, in one unit pixel P inthe solid-state imaging element (solid-state imaging device 1) such as abackside illumination type CCD image sensor or CMOS image sensor,similarly to the photoelectric conversion element 10 according to theabove-described embodiment, etc. The photoelectric conversion element 20according to the present modification example has a configuration inwhich a red photoelectric conversion section 40R, a green photoelectricconversion section 40G, and a blue photoelectric conversion section 40Bare stacked in this order on a silicon substrate 81 with the insulatinglayer 82 interposed therebetween.

The red photoelectric conversion section 40R, the green photoelectricconversion section 40G, and the blue photoelectric conversion section40B respectively include organic photoelectric conversion layers 42R,42G, and 42B between the respective pairs of electrodes. Specifically,the red photoelectric conversion section 40R, the green photoelectricconversion section 40G, and the blue photoelectric conversion section40B respectively include the organic photoelectric conversion layers42R, 42G, and 42B between a first electrode 41R and a second electrode43R, between a first electrode 41G and a second electrode 43G, andbetween a first electrode 41B and a second electrode 43B. The organicphotoelectric conversion layers 42R, 42G, and 42B each include a ChDTderivative, making it possible to obtain effects similar to those of theabove-described embodiment.

As described above, the photoelectric conversion element 20 has aconfiguration in which the red photoelectric conversion section 40R, thegreen photoelectric conversion section 40G, and the blue photoelectricconversion section 40B are stacked in this order on the siliconsubstrate 81 with the insulating layer 82 interposed therebetween. Theon-chip lens 19L is provided on the blue photoelectric conversionsection 40B with the protective layer 18 and the on-chip lens layer 19interposed therebetween. A red electricity storage layer 210R, a greenelectricity storage layer 210G, and a blue electricity storage layer210B are provided in the silicon substrate 81. The pieces of lightinputted into the on-chip lens 19L are photoelectrically converted bythe red photoelectric conversion section 40R, the green photoelectricconversion section 40G, and the blue photoelectric conversion section40B. The respective signal charges are transmitted from the redphotoelectric conversion section 40R to the red electricity storagelayer 210R, from the green photoelectric conversion section 40G to thegreen electricity storage layer 210G, and from the blue photoelectricconversion section 40B to the blue electricity storage layer 210B.Although the signal charges may be either electrons or holes generatedby photoelectric conversion, the following gives description byexemplifying a case where electrons are read as signal charges.

The silicon substrate 81 includes, for example, a p-type siliconsubstrate. The red electricity storage layer 210R, the green electricitystorage layer 210G, and the blue electricity storage layer 210B providedin this silicon substrate 81 each include an n-type semiconductorregion. The respective signal charges (electrons) supplied from the redphotoelectric conversion section 40R, the green photoelectric conversionsection 40G, and the blue photoelectric conversion section 40B areaccumulated in the n-type semiconductor regions. The n-typesemiconductor regions of the red electricity storage layer 210R, thegreen electricity storage layer 210G, and the blue electricity storagelayer 210B are formed, for example, by doping the silicon substrate 81with n-type impurities such as phosphorus (P) or arsenic (As). It is tobe noted that the silicon substrate 81 may be provided on a supportsubstrate (not illustrated) of glass, or the like.

The silicon substrate 81 includes a pixel transistor for reading therespective electrons from the red electricity storage layer 210R, thegreen electricity storage layer 210G, and the blue electricity storagelayer 210B and transferring the read electrons to, for example, avertical signal line (vertical signal line Lsig in FIG. 8 describedbelow). A floating diffusion of this pixel transistor is provided in thesilicon substrate 81, and this floating diffusion is coupled to the redelectricity storage layer 210R, the green electricity storage layer210G, and the blue electricity storage layer 210B. The floatingdiffusion includes an n-type semiconductor region.

The insulating layer 82 includes, for example, silicon oxide, siliconnitride, silicon oxynitride, hafnium oxide, or the like. The insulatinglayer 82 may include a plurality of types of insulating films that isstacked. The insulating layer 82 may include an organic insulatingmaterial. This insulating layer 82 includes respective plugs andrespective electrodes for coupling the red electricity storage layer210R and the red photoelectric conversion section 40R, the greenelectricity storage layer 210G and the green photoelectric conversionsection 40G, and the blue electricity storage layer 210B and the bluephotoelectric conversion section 40B.

The red photoelectric conversion section 40R includes the firstelectrode 41R, an organic photoelectric conversion layer 42R, and thesecond electrode 43R in this order from a position close to the siliconsubstrate 81. The green photoelectric conversion section 40G includesthe first electrode 41G, an organic photoelectric conversion layer 42G,and the second electrode 43G in this order from a position close to thered photoelectric conversion section 40R. The blue photoelectricconversion section 40B includes the first electrode 41B, an organicphotoelectric conversion layer 42B, and the second electrode 43B in thisorder from a position close to the green photoelectric conversionsection 40G. An insulating layer 44 is provided between the redphotoelectric conversion section 40R and the green photoelectricconversion section 40G, and an insulating layer 45 is provided betweenthe green photoelectric conversion section 40G and the bluephotoelectric conversion section 40B. Light of red (e.g., wavelength of600 nm or more and less than 700 nm) is selectively absorbed in the redphotoelectric conversion section 40R; light of green (e.g., wavelengthof 480 nm or more and less than 600 nm) is selectively absorbed in thegreen photoelectric conversion section 40G; and light of blue (e.g.,wavelength of 400 nm or more and less than 480 nm) is selectivelyabsorbed in the blue photoelectric conversion section 40B, generatingelectron-hole pairs.

The first electrode 41R extracts signal charges generated in the organicphotoelectric conversion layer 42R; the first electrode 41G extractssignal charges generated in the organic photoelectric conversion layer42G; and the first electrode 41B extracts signal charges generated inthe organic photoelectric conversion layer 42B. The first electrodes41R, 41G, and 41B are each provided for each pixel, for example. Thesefirst electrodes 41R, 41G, and 41B each include, for example, alight-transmissive electrically-conductive material, specifically, ITO.The first electrodes 41R, 41G, and 41B may each include, for example, atin oxide-based material or a zinc oxide-based material. The tinoxide-based material is obtained by doping tin oxide with a dopant.Examples of the zinc oxide-based material include aluminum zinc oxide inwhich aluminum is added to zinc oxide as a dopant, gallium zinc oxide inwhich gallium is added to zinc oxide as a dopant, indium zinc oxide inwhich indium is added to zinc oxide as a dopant, and the like.Alternatively, it is also be possible to use IGZO, CuI, InSbO₄, ZnMgO,CuInO₂, MgIn₂O₄, CdO, ZnSnO₃, and the like. The thickness of each of thefirst electrodes 41R, 41G, and 41B is, for example, 50 nm to 500 nm.

For example, respective electron transport layers may be providedbetween the first electrode 41R and the organic photoelectric conversionlayer 42R, between the first electrode 41G and the organic photoelectricconversion layer 42G, and between the first electrode 41B and theorganic photoelectric conversion layer 42B. The electron transportlayers serve to facilitate electrons generated in the organicphotoelectric conversion layers 42R, 42G, and 42B to be supplied to thefirst electrodes 41R, 41G, and 41B, and each include, for example,titanium oxide, zinc oxide, or the like. The electron transport layersmay each include titanium oxide and zinc oxide that are stacked. Thethickness of each of the electron transport layers is, for example, 0.1nm to 1000 nm, and preferably 0.5 nm to 300 nm.

The organic photoelectric conversion layers 42R, 42G, and 42B eachabsorb light in a selective wavelength region for photoelectricconversion, and transmit light in another wavelength region. Here, thelight in the selective wavelength region is, for example, light in awavelength region of a wavelength of 600 nm or more and less than 700 nmin the organic photoelectric conversion layer 42R, light in a wavelengthregion of a wavelength of 480 nm or more and less than 600 nm, forexample, in the organic photoelectric conversion layer 42G, and light ina wavelength region of a wavelength of 400 nm or more and less than 480nm, for example, in the organic photoelectric conversion layer 42B. Thethickness of each of the organic photoelectric conversion layers 42R,42G, and 42B is, for example, 50 nm or more and less than 500 nm.

The organic photoelectric conversion layers 42R, 42G, and 42B eachinclude, for example, two or more types of organic semiconductormaterials, and preferably includes, for example, one or both of a p-typesemiconductor and an n-type semiconductor, similarly to the organicphotoelectric conversion layer 16 in the above-described embodiment. Forexample, in a case where each of the organic photoelectric conversionlayers 42R, 42G, and 42B includes the two types of organic semiconductormaterials including a p-type semiconductor and an n-type semiconductor,for example, one of the p-type semiconductor and the n-typesemiconductor is preferably a material having transmissivity to visiblelight, and the other thereof is preferably a material thatphotoelectrically converts light in a selective wavelength region (e.g.,450 nm or more and 650 nm or less). Alternatively, each of the organicphotoelectric conversion layers 42R, 42G, and 42B preferably includesthree types of organic semiconductor materials including a material(light absorber), an n-type semiconductor, and a p-type semiconductor.The material (light absorber) photoelectrically converts light in aselective wavelength region corresponding to each layer. The n-typesemiconductor and the p-type semiconductor each havelight-transmissivity to visible light.

Each of the organic photoelectric conversion layers 42R, 42G, and 42Bhas a bulk heterostructure in which the plurality of these organicsemiconductor materials is randomly mixed in the layer. In the presentmodification example, at least one of the organic photoelectricconversion layers 42R, 42G, and 42B has a configuration in which adomain (e.g., domain Dp) having a configuration similar to that of theorganic photoelectric conversion layer 16 according to theabove-described embodiment is formed in the layer.

For example, respective hole transport layers may be provided betweenthe organic photoelectric conversion layer 42R and the second electrode43R, between the organic photoelectric conversion layer 42G and thesecond electrode 43G, and between the organic photoelectric conversionlayer 42B and the second electrode 43B. The hole transport layers serveto facilitate holes generated in the organic photoelectric conversionlayers 42R, 42G, and 42B to be supplied to the second electrodes 43R,43G, and 43B, and each include, for example, molybdenum oxide, nickeloxide, vanadium oxide, or the like. The hole transport layers may eachinclude an organic material such as PEDOT(Poly(3,4-ethylenedioxythiophene) and TPD(N,N′-Bis(3-methylphenyl)-N,N′-diphenylbenzidine). The thickness of eachof the hole transport layers is, for example, 0.5 nm or more and 100 nmor less.

The second electrode 43R serves to extract holes generated in theorganic photoelectric conversion layer 42R; the second electrode 43Gserves to extract holes generated in the organic photoelectricconversion layer 42G; and the second electrode 43B serves to extractholes generated in the organic photoelectric conversion layer 42G. Theholes extracted from the second electrodes 43R, 43G, and 43B aredischarged to, for example, a p-type semiconductor region (notillustrated) in the silicon substrate 81 via respective transmissionpaths (not illustrated). The second electrodes 43R, 43G, and 43B eachinclude, for example, an electrically-conductive material such as gold,silver, copper, and aluminum. Similarly to the first electrodes 41R,41G, and 41B, the second electrodes 43R, 43G, and 43B may each include atransparent electrically-conductive material. In the photoelectricconversion element 20, holes extracted from these second electrodes 43R,43G, and 43B are discharged. Therefore, for example, when the pluralityof photoelectric conversion elements 20 is disposed in the solid-stateimaging device 1 described below, the second electrodes 43R, 43G, and43B may be provided in common for each of the photoelectric conversionelements 20 (unit pixel P). The thickness of each of the secondelectrodes 43R, 43G, and 43B is, for example, 0.5 nm or more and 100 nmor less.

The insulating layer 44 serves to insulate the second electrode 43R andthe first electrode 41G from each other, and the insulating layer 45serves to insulate the second electrode 43G and the first electrode 41Bfrom each other. The insulating layers 44 and 45 each include, forexample, a metal oxide, a metal sulfide, or an organic material.Examples of the metal oxide include silicon oxide, aluminum oxide,zirconium oxide, titanium oxide, zinc oxide, tungsten oxide, magnesiumoxide, niobium oxide, tin oxide, gallium oxide, and the like. Examplesof the metal sulfide include zinc sulfide, magnesium sulfide, and thelike. The band gap of a material included in each of the insulatinglayers 44 and 45 is preferably 3.0 eV or more. The thickness of each ofthe insulating layers 44 and, 45 is, for example, 2 nm or more and 100nm or less.

As described above, an organic semiconductor material is used that formsa domain having a percolation structure and having a shape in which thelength of the domain in the plane direction is less than the length ofthe domain in the film-thickness direction in at least one of theorganic photoelectric conversion layers 42R, 42G, and 42B. In thepercolation structure, the domain vertically extends in the organicphotoelectric conversion layer (e.g., organic photoelectric conversionlayer 42R) in the film-thickness direction. This causes organicsemiconductor materials (e.g., an n-type semiconductor and a lightabsorber in addition to the above-described p-type semiconductor)included in an organic photoelectric conversion layer (e.g., organicphotoelectric conversion layer 42R) to be controlled in an appropriatemixture state. This makes it possible to increase the external quantumefficiency and response speed.

3. Application Examples Application Example 1

FIG. 8 illustrates, for example, an overall configuration of thesolid-state imaging device 1 including the photoelectric conversionelement 10 described in the above-described embodiment for each pixel.This solid-state imaging device 1 is a CMOS image sensor. Thesolid-state imaging device 1 includes, on the semiconductor substrate11, the pixel section 1 a as an imaging area, and a peripheral circuitunit 130 in a peripheral region of this pixel section 1 a. Theperipheral circuit unit 130 includes, for example, a row scanningsection 131, a horizontal selection section 133, a column scanningsection 134, and a system control section 132.

The pixel section 1 a includes, for example, a plurality of unit pixelsP (corresponding to, for example, the photoelectric conversion elements10) that are two-dimensionally disposed in matrix. In these unit pixelsP, pixel drive lines Lread (specifically, row selection lines and resetcontrol lines) are disposed at each of pixel rows, for example, andvertical signal lines Lsig are disposed at each of pixel columns. Thepixel drive lines Lread are each used to transmit drive signals forreading signals from pixels. One end of each of the pixel drive linesLread is coupled to the output end of the row scanning section 131corresponding to each row.

The row scanning section 131 is a pixel drive section that includes ashift register, an address decoder, and the like, and drives each of theunit pixels P of the pixel section 1 a on a row basis, for example. Asignal outputted from each of the unit pixels P of the pixel rowsselected and scanned by the row scanning section 131 is supplied to thehorizontal selection section 133 through each of the vertical signallines Lsig. The horizontal selection section 133 includes an amplifier,a horizontal selection switch, and the like provided for each of thevertical signal lines Lsig.

The column scanning section 134 includes a shift register, an addressdecoder, and the like, and drives each of the horizontal selectionswitches of the horizontal selection section 133 in sequence whilescanning the horizontal selection switches. Selection and scanning bythis column scanning section 134 output signals of the respective pixelstransmitted through each of the vertical signal lines Lsig to ahorizontal signal line 135 in sequence, and transmits the signals to theoutside of the semiconductor substrate 11 through the horizontal signalline 135.

Circuit portions including the row scanning section 131, the horizontalselection section 133, the column scanning section 134, and thehorizontal signal line 135 may be formed directly on the semiconductorsubstrate 11 or may be disposed on external control IC. In addition,those circuit portions may be formed on another substrate coupled by acable or the like.

The system control section 132 receives, for example, a clock, data foran instruction about an operation mode, and the like. The clock and thedata are supplied from the outside of the semiconductor substrate 11. Inaddition, the system control section 132 outputs data such as internalinformation of the solid-state imaging device 1. The system controlsection 132 further includes a timing generator that generates varioustiming signals, and controls the driving of the peripheral circuit suchas the row scanning section 131, the horizontal selection section 133,and the column scanning section 134 on the basis of the various timingsignals generated by the timing generator.

Application Example 2

The above-described solid-state imaging device 1 is applicable to, forexample, any type of electronic apparatus (solid-state imaging device)having an imaging function. The electronic apparatus (solid-stateimaging device) includes a camera system such as a digital still cameraand a video camera, a mobile phone having the imaging function, and thelike. FIG. 9 illustrates a schematic configuration of a camera 2 as anexample thereof. This camera 2 is, for example, a video camera that isable to capture a still image or a moving image. The camera 2 includesthe solid-state imaging device 1, an optical system (optical lens) 310,a shutter device 311, a drive section 313 that drives the solid-stateimaging device 1 and the shutter device 311, and a signal processingsection 312.

The optical system 310 guides image light (incident light) from anobject to the pixel section 1 a of the solid-state imaging device 1.This optical system 310 may include a plurality of optical lenses. Theshutter device 311 controls a period of time in which the solid-stateimaging device 1 is irradiated with light and a period of time in whichlight is blocked. The drive section 313 controls a transfer operation ofthe solid-state imaging device 1 and a shutter operation of the shutterdevice 311. The signal processing section 312 performs various types ofsignal processing on signals outputted from the solid-state imagingdevice 1. An image signal Dout subjected to the signal processing isstored in a storage medium such as a memory or outputted to a monitor orthe like.

Application Example 3 <Example of Application to In-Vivo InformationAcquisition System>

Further, the technology (present technology) according to the presentdisclosure is applicable to various products. For example, thetechnology according to the present disclosure may be applied to anendoscopic surgery system.

FIG. 10 is a block diagram depicting an example of a schematicconfiguration of an in-vivo information acquisition system of a patientusing a capsule type endoscope, to which the technology according to anembodiment of the present disclosure (present technology) can beapplied.

The in-vivo information acquisition system 10001 includes a capsule typeendoscope 10100 and an external controlling apparatus 10200.

The capsule type endoscope 10100 is swallowed by a patient at the timeof inspection. The capsule type endoscope 10100 has an image pickupfunction and a wireless communication function and successively picks upan image of the inside of an organ such as the stomach or an intestine(hereinafter referred to as in-vivo image) at predetermined intervalswhile it moves inside of the organ by peristaltic motion for a period oftime until it is naturally discharged from the patient. Then, thecapsule type endoscope 10100 successively transmits information of thein-vivo image to the external controlling apparatus 10200 outside thebody by wireless transmission.

The external controlling apparatus 10200 integrally controls operationof the in-vivo information acquisition system 10001. Further, theexternal controlling apparatus 10200 receives information of an in-vivoimage transmitted thereto from the capsule type endoscope 10100 andgenerates image data for displaying the in-vivo image on a displayapparatus (not depicted) on the basis of the received information of thein-vivo image.

In the in-vivo information acquisition system 10001, an in-vivo imageimaged a state of the inside of the body of a patient can be acquired atany time in this manner for a period of time until the capsule typeendoscope 10100 is discharged after it is swallowed.

A configuration and functions of the capsule type endoscope 10100 andthe external controlling apparatus 10200 are described in more detailbelow.

The capsule type endoscope 10100 includes a housing 10101 of the capsuletype, in which a light source unit 10111, an image pickup unit 10112, animage processing unit 10113, a wireless communication unit 10114, apower feeding unit 10115, a power supply unit 10116 and a control unit10117 are accommodated.

The light source unit 10111 includes a light source such as, forexample, a light emitting diode (LED) and irradiates light on an imagepickup field-of-view of the image pickup unit 10112.

The image pickup unit 10112 includes an image pickup element and anoptical system including a plurality of lenses provided at a precedingstage to the image pickup element. Reflected light (hereinafter referredto as observation light) of light irradiated on a body tissue which isan observation target is condensed by the optical system and introducedinto the image pickup element. In the image pickup unit 10112, theincident observation light is photoelectrically converted by the imagepickup element, by which an image signal corresponding to theobservation light is generated. The image signal generated by the imagepickup unit 10112 is provided to the image processing unit 10113.

The image processing unit 10113 includes a processor such as a centralprocessing unit (CPU) or a graphics processing unit (GPU) and performsvarious signal processes for an image signal generated by the imagepickup unit 10112. The image processing unit 10113 provides the imagesignal for which the signal processes have been performed thereby as RAWdata to the wireless communication unit 10114.

The wireless communication unit 10114 performs a predetermined processsuch as a modulation process for the image signal for which the signalprocesses have been performed by the image processing unit 10113 andtransmits the resulting image signal to the external controllingapparatus 10200 through an antenna 10114A. Further, the wirelesscommunication unit 10114 receives a control signal relating to drivingcontrol of the capsule type endoscope 10100 from the externalcontrolling apparatus 10200 through the antenna 10114A. The wirelesscommunication unit 10114 provides the control signal received from theexternal controlling apparatus 10200 to the control unit 10117.

The power feeding unit 10115 includes an antenna coil for powerreception, a power regeneration circuit for regenerating electric powerfrom current generated in the antenna coil, a voltage booster circuitand so forth. The power feeding unit 10115 generates electric powerusing the principle of non-contact charging.

The power supply unit 10116 includes a secondary battery and storeselectric power generated by the power feeding unit 10115. In FIG. 10, inorder to avoid complicated illustration, an arrow mark indicative of asupply destination of electric power from the power supply unit 10116and so forth are omitted. However, electric power stored in the powersupply unit 10116 is supplied to and can be used to drive the lightsource unit 10111, the image pickup unit 10112, the image processingunit 10113, the wireless communication unit 10114 and the control unit10117.

The control unit 10117 includes a processor such as a CPU and suitablycontrols driving of the light source unit 10111, the image pickup unit10112, the image processing unit 10113, the wireless communication unit10114 and the power feeding unit 10115 in accordance with a controlsignal transmitted thereto from the external controlling apparatus10200.

The external controlling apparatus 10200 includes a processor such as aCPU or a GPU, a microcomputer, a control board or the like in which aprocessor and a storage element such as a memory are mixedlyincorporated. The external controlling apparatus 10200 transmits acontrol signal to the control unit 10117 of the capsule type endoscope10100 through an antenna 10200A to control operation of the capsule typeendoscope 10100. In the capsule type endoscope 10100, an irradiationcondition of light upon an observation target of the light source unit10111 can be changed, for example, in accordance with a control signalfrom the external controlling apparatus 10200. Further, an image pickupcondition (for example, a frame rate, an exposure value or the like ofthe image pickup unit 10112) can be changed in accordance with a controlsignal from the external controlling apparatus 10200. Further, thesubstance of processing by the image processing unit 10113 or acondition for transmitting an image signal from the wirelesscommunication unit 10114 (for example, a transmission interval, atransmission image number or the like) may be changed in accordance witha control signal from the external controlling apparatus 10200.

Further, the external controlling apparatus 10200 performs various imageprocesses for an image signal transmitted thereto from the capsule typeendoscope 10100 to generate image data for displaying a picked upin-vivo image on the display apparatus. As the image processes, varioussignal processes can be performed such as, for example, a developmentprocess (demosaic process), an image quality improving process(bandwidth enhancement process, a super-resolution process, a noisereduction (NR) process and/or image stabilization process) and/or anenlargement process (electronic zooming process). The externalcontrolling apparatus 10200 controls driving of the display apparatus tocause the display apparatus to display a picked up in-vivo image on thebasis of generated image data. Alternatively, the external controllingapparatus 10200 may also control a recording apparatus (not depicted) torecord generated image data or control a printing apparatus (notdepicted) to output generated image data by printing.

An example of the in-vivo information acquisition system to which thetechnology according to the present disclosure may be applied has beendescribed above. The technology according to the present disclosure maybe applied, for example, to the image pickup unit 10112 among thecomponents described above. This makes it possible to increase thedetection accuracy.

Application Example 4 4. Example of Application to Endoscopic SurgerySystem

The technology (present technology) according to the present disclosureis applicable to various products. For example, the technology accordingto the present disclosure may be applied to an endoscopic surgerysystem.

FIG. 11 is a view depicting an example of a schematic configuration ofan endoscopic surgery system to which the technology according to anembodiment of the present disclosure (present technology) can beapplied.

In FIG. 11, a state is illustrated in which a surgeon (medical doctor)11131 is using an endoscopic surgery system 11000 to perform surgery fora patient 11132 on a patient bed 11133. As depicted, the endoscopicsurgery system 11000 includes an endoscope 11100, other surgical tools11110 such as a pneumoperitoneum tube 11111 and an energy device 11112,a supporting arm apparatus 11120 which supports the endoscope 11100thereon, and a cart 11200 on which various apparatus for endoscopicsurgery are mounted.

The endoscope 11100 includes a lens barrel 11101 having a region of apredetermined length from a distal end thereof to be inserted into abody cavity of the patient 11132, and a camera head 11102 connected to aproximal end of the lens barrel 11101. In the example depicted, theendoscope 11100 is depicted which includes as a rigid endoscope havingthe lens barrel 11101 of the hard type. However, the endoscope 11100 mayotherwise be included as a flexible endoscope having the lens barrel11101 of the flexible type.

The lens barrel 11101 has, at a distal end thereof, an opening in whichan objective lens is fitted. A light source apparatus 11203 is connectedto the endoscope 11100 such that light generated by the light sourceapparatus 11203 is introduced to a distal end of the lens barrel 11101by a light guide extending in the inside of the lens barrel 11101 and isirradiated toward an observation target in a body cavity of the patient11132 through the objective lens. It is to be noted that the endoscope11100 may be a forward-viewing endoscope or may be an oblique-viewingendoscope or a side-viewing endoscope.

An optical system and an image pickup element are provided in the insideof the camera head 11102 such that reflected light (observation light)from the observation target is condensed on the image pickup element bythe optical system. The observation light is photo-electricallyconverted by the image pickup element to generate an electric signalcorresponding to the observation light, namely, an image signalcorresponding to an observation image. The image signal is transmittedas RAW data to a CCU 11201.

The CCU 11201 includes a central processing unit (CPU), a graphicsprocessing unit (GPU) or the like and integrally controls operation ofthe endoscope 11100 and a display apparatus 11202. Further, the CCU11201 receives an image signal from the camera head 11102 and performs,for the image signal, various image processes for displaying an imagebased on the image signal such as, for example, a development process(demosaic process).

The display apparatus 11202 displays thereon an image based on an imagesignal, for which the image processes have been performed by the CCU11201, under the control of the CCU 11201.

The light source apparatus 11203 includes a light source such as, forexample, a light emitting diode (LED) and supplies irradiation lightupon imaging of a surgical region to the endoscope 11100.

An inputting apparatus 11204 is an input interface for the endoscopicsurgery system 11000. A user can perform inputting of various kinds ofinformation or instruction inputting to the endoscopic surgery system11000 through the inputting apparatus 11204. For example, the user wouldinput an instruction or a like to change an image pickup condition (typeof irradiation light, magnification, focal distance or the like) by theendoscope 11100.

A treatment tool controlling apparatus 11205 controls driving of theenergy device 11112 for cautery or incision of a tissue, sealing of ablood vessel or the like. A pneumoperitoneum apparatus 11206 feeds gasinto a body cavity of the patient 11132 through the pneumoperitoneumtube 11111 to inflate the body cavity in order to secure the field ofview of the endoscope 11100 and secure the working space for thesurgeon. A recorder 11207 is an apparatus capable of recording variouskinds of information relating to surgery. A printer 11208 is anapparatus capable of printing various kinds of information relating tosurgery in various forms such as a text, an image or a graph.

It is to be noted that the light source apparatus 11203 which suppliesirradiation light when a surgical region is to be imaged to theendoscope 11100 may include a white light source which includes, forexample, an LED, a laser light source or a combination of them. Where awhite light source includes a combination of red, green, and blue (RGB)laser light sources, since the output intensity and the output timingcan be controlled with a high degree of accuracy for each color (eachwavelength), adjustment of the white balance of a picked up image can beperformed by the light source apparatus 11203. Further, in this case, iflaser beams from the respective RGB laser light sources are irradiatedtime-divisionally on an observation target and driving of the imagepickup elements of the camera head 11102 are controlled in synchronismwith the irradiation timings. Then images individually corresponding tothe R, G and B colors can be also picked up time-divisionally. Accordingto this method, a color image can be obtained even if color filters arenot provided for the image pickup element.

Further, the light source apparatus 11203 may be controlled such thatthe intensity of light to be outputted is changed for each predeterminedtime. By controlling driving of the image pickup element of the camerahead 11102 in synchronism with the timing of the change of the intensityof light to acquire images time-divisionally and synthesizing theimages, an image of a high dynamic range free from underexposed blockedup shadows and overexposed highlights can be created.

Further, the light source apparatus 11203 may be configured to supplylight of a predetermined wavelength band ready for special lightobservation. In special light observation, for example, by utilizing thewavelength dependency of absorption of light in a body tissue toirradiate light of a narrow band in comparison with irradiation lightupon ordinary observation (namely, white light), narrow band observation(narrow band imaging) of imaging a predetermined tissue such as a bloodvessel of a superficial portion of the mucous membrane or the like in ahigh contrast is performed. Alternatively, in special light observation,fluorescent observation for obtaining an image from fluorescent lightgenerated by irradiation of excitation light may be performed. Influorescent observation, it is possible to perform observation offluorescent light from a body tissue by irradiating excitation light onthe body tissue (autofluorescence observation) or to obtain afluorescent light image by locally injecting a reagent such asindocyanine green (ICG) into a body tissue and irradiating excitationlight corresponding to a fluorescent light wavelength of the reagentupon the body tissue. The light source apparatus 11203 can be configuredto supply such narrow-band light and/or excitation light suitable forspecial light observation as described above.

FIG. 12 is a block diagram depicting an example of a functionalconfiguration of the camera head 11102 and the CCU 11201 depicted inFIG. 11.

The camera head 11102 includes a lens unit 11401, an image pickup unit11402, a driving unit 11403, a communication unit 11404 and a camerahead controlling unit 11405. The CCU 11201 includes a communication unit11411, an image processing unit 11412 and a control unit 11413. Thecamera head 11102 and the CCU 11201 are connected for communication toeach other by a transmission cable 11400.

The lens unit 11401 is an optical system, provided at a connectinglocation to the lens barrel 11101. Observation light taken in from adistal end of the lens barrel 11101 is guided to the camera head 11102and introduced into the lens unit 11401. The lens unit 11401 includes acombination of a plurality of lenses including a zoom lens and afocusing lens.

The number of image pickup elements which is included by the imagepickup unit 11402 may be one (single-plate type) or a plural number(multi-plate type). Where the image pickup unit 11402 is configured asthat of the multi-plate type, for example, image signals correspondingto respective R, G and B are generated by the image pickup elements, andthe image signals may be synthesized to obtain a color image. The imagepickup unit 11402 may also be configured so as to have a pair of imagepickup elements for acquiring respective image signals for the right eyeand the left eye ready for three dimensional (3D) display. If 3D displayis performed, then the depth of a living body tissue in a surgicalregion can be comprehended more accurately by the surgeon 11131. It isto be noted that, where the image pickup unit 11402 is configured asthat of stereoscopic type, a plurality of systems of lens units 11401are provided corresponding to the individual image pickup elements.

Further, the image pickup unit 11402 may not necessarily be provided onthe camera head 11102. For example, the image pickup unit 11402 may beprovided immediately behind the objective lens in the inside of the lensbarrel 11101.

The driving unit 11403 includes an actuator and moves the zoom lens andthe focusing lens of the lens unit 11401 by a predetermined distancealong an optical axis under the control of the camera head controllingunit 11405. Consequently, the magnification and the focal point of apicked up image by the image pickup unit 11402 can be adjusted suitably.

The communication unit 11404 includes a communication apparatus fortransmitting and receiving various kinds of information to and from theCCU 11201. The communication unit 11404 transmits an image signalacquired from the image pickup unit 11402 as RAW data to the CCU 11201through the transmission cable 11400.

In addition, the communication unit 11404 receives a control signal forcontrolling driving of the camera head 11102 from the CCU 11201 andsupplies the control signal to the camera head controlling unit 11405.The control signal includes information relating to image pickupconditions such as, for example, information that a frame rate of apicked up image is designated, information that an exposure value uponimage picking up is designated and/or information that a magnificationand a focal point of a picked up image are designated.

It is to be noted that the image pickup conditions such as the framerate, exposure value, magnification or focal point may be designated bythe user or may be set automatically by the control unit 11413 of theCCU 11201 on the basis of an acquired image signal. In the latter case,an auto exposure (AE) function, an auto focus (AF) function and an autowhite balance (AWB) function are incorporated in the endoscope 11100.

The camera head controlling unit 11405 controls driving of the camerahead 11102 on the basis of a control signal from the CCU 11201 receivedthrough the communication unit 11404.

The communication unit 11411 includes a communication apparatus fortransmitting and receiving various kinds of information to and from thecamera head 11102. The communication unit 11411 receives an image signaltransmitted thereto from the camera head 11102 through the transmissioncable 11400.

Further, the communication unit 11411 transmits a control signal forcontrolling driving of the camera head 11102 to the camera head 11102.The image signal and the control signal can be transmitted by electricalcommunication, optical communication or the like.

The image processing unit 11412 performs various image processes for animage signal in the form of RAW data transmitted thereto from the camerahead 11102.

The control unit 11413 performs various kinds of control relating toimage picking up of a surgical region or the like by the endoscope 11100and display of a picked up image obtained by image picking up of thesurgical region or the like. For example, the control unit 11413 createsa control signal for controlling driving of the camera head 11102.

Further, the control unit 11413 controls, on the basis of an imagesignal for which image processes have been performed by the imageprocessing unit 11412, the display apparatus 11202 to display a pickedup image in which the surgical region or the like is imaged. Thereupon,the control unit 11413 may recognize various objects in the picked upimage using various image recognition technologies. For example, thecontrol unit 11413 can recognize a surgical tool such as forceps, aparticular living body region, bleeding, mist when the energy device11112 is used and so forth by detecting the shape, color and so forth ofedges of objects included in a picked up image. The control unit 11413may cause, when it controls the display apparatus 11202 to display apicked up image, various kinds of surgery supporting information to bedisplayed in an overlapping manner with an image of the surgical regionusing a result of the recognition. Where surgery supporting informationis displayed in an overlapping manner and presented to the surgeon11131, the burden on the surgeon 11131 can be reduced and the surgeon11131 can proceed with the surgery with certainty.

The transmission cable 11400 which connects the camera head 11102 andthe CCU 11201 to each other is an electric signal cable ready forcommunication of an electric signal, an optical fiber ready for opticalcommunication or a composite cable ready for both of electrical andoptical communications.

Here, while, in the example depicted, communication is performed bywired communication using the transmission cable 11400, thecommunication between the camera head 11102 and the CCU 11201 may beperformed by wireless communication.

An example of the endoscopic surgery system to which the technologyaccording to the present disclosure may be applied has been describedabove. The technology according to the present disclosure may be appliedto the image pickup unit 11402 among the components described above.Applying the technology according to an embodiment of the presentdisclosure to the image pickup unit 11402 increases the detectionaccuracy.

It is to be noted that the endoscopic surgery system has been describedhere as an example, but the technology according to the presentdisclosure may be additionally applied to, for example, a microscopicsurgery system or the like.

Application Example 5 <Example of Application to Mobile Body>

The technology according to the present disclosure is applicable tovarious products. For example, the technology according to the presentdisclosure may be achieved as a device mounted on any type of mobilebody such as a vehicle, an electric vehicle, a hybrid electric vehicle,a motorcycle, a bicycle, a personal mobility, an airplane, a drone, avessel, a robot, a construction machine, or an agricultural machine(tractor).

FIG. 13 is a block diagram depicting an example of schematicconfiguration of a vehicle control system as an example of a mobile bodycontrol system to which the technology according to an embodiment of thepresent disclosure can be applied.

The vehicle control system 12000 includes a plurality of electroniccontrol units connected to each other via a communication network 12001.In the example depicted in FIG. 13, the vehicle control system 12000includes a driving system control unit 12010, a body system control unit12020, an outside-vehicle information detecting unit 12030, anin-vehicle information detecting unit 12040, and an integrated controlunit 12050. In addition, a microcomputer 12051, a sound/image outputsection 12052, and a vehicle-mounted network interface (I/F) 12053 areillustrated as a functional configuration of the integrated control unit12050.

The driving system control unit 12010 controls the operation of devicesrelated to the driving system of the vehicle in accordance with variouskinds of programs. For example, the driving system control unit 12010functions as a control device for a driving force generating device forgenerating the driving force of the vehicle, such as an internalcombustion engine, a driving motor, or the like, a driving forcetransmitting mechanism for transmitting the driving force to wheels, asteering mechanism for adjusting the steering angle of the vehicle, abraking device for generating the braking force of the vehicle, and thelike.

The body system control unit 12020 controls the operation of variouskinds of devices provided to a vehicle body in accordance with variouskinds of programs. For example, the body system control unit 12020functions as a control device for a keyless entry system, a smart keysystem, a power window device, or various kinds of lamps such as aheadlamp, a backup lamp, a brake lamp, a turn signal, a fog lamp, or thelike. In this case, radio waves transmitted from a mobile device as analternative to a key or signals of various kinds of switches can beinput to the body system control unit 12020. The body system controlunit 12020 receives these input radio waves or signals, and controls adoor lock device, the power window device, the lamps, or the like of thevehicle.

The outside-vehicle information detecting unit 12030 detects informationabout the outside of the vehicle including the vehicle control system12000. For example, the outside-vehicle information detecting unit 12030is connected with an imaging section 12031. The outside-vehicleinformation detecting unit 12030 makes the imaging section 12031 imagean image of the outside of the vehicle, and receives the imaged image.On the basis of the received image, the outside-vehicle informationdetecting unit 12030 may perform processing of detecting an object suchas a human, a vehicle, an obstacle, a sign, a character on a roadsurface, or the like, or processing of detecting a distance thereto.

The imaging section 12031 is an optical sensor that receives light, andwhich outputs an electric signal corresponding to a received lightamount of the light. The imaging section 12031 can output the electricsignal as an image, or can output the electric signal as informationabout a measured distance. In addition, the light received by theimaging section 12031 may be visible light, or may be invisible lightsuch as infrared rays or the like.

The in-vehicle information detecting unit 12040 detects informationabout the inside of the vehicle. The in-vehicle information detectingunit 12040 is, for example, connected with a driver state detectingsection 12041 that detects the state of a driver. The driver statedetecting section 12041, for example, includes a camera that images thedriver. On the basis of detection information input from the driverstate detecting section 12041, the in-vehicle information detecting unit12040 may calculate a degree of fatigue of the driver or a degree ofconcentration of the driver, or may determine whether the driver isdozing.

The microcomputer 12051 can calculate a control target value for thedriving force generating device, the steering mechanism, or the brakingdevice on the basis of the information about the inside or outside ofthe vehicle which information is obtained by the outside-vehicleinformation detecting unit 12030 or the in-vehicle information detectingunit 12040, and output a control command to the driving system controlunit 12010. For example, the microcomputer 12051 can perform cooperativecontrol intended to implement functions of an advanced driver assistancesystem (ADAS) which functions include collision avoidance or shockmitigation for the vehicle, following driving based on a followingdistance, vehicle speed maintaining driving, a warning of collision ofthe vehicle, a warning of deviation of the vehicle from a lane, or thelike.

In addition, the microcomputer 12051 can perform cooperative controlintended for automatic driving, which makes the vehicle to travelautonomously without depending on the operation of the driver, or thelike, by controlling the driving force generating device, the steeringmechanism, the braking device, or the like on the basis of theinformation about the outside or inside of the vehicle which informationis obtained by the outside-vehicle information detecting unit 12030 orthe in-vehicle information detecting unit 12040.

In addition, the microcomputer 12051 can output a control command to thebody system control unit 12020 on the basis of the information about theoutside of the vehicle which information is obtained by theoutside-vehicle information detecting unit 12030. For example, themicrocomputer 12051 can perform cooperative control intended to preventa glare by controlling the headlamp so as to change from a high beam toa low beam, for example, in accordance with the position of a precedingvehicle or an oncoming vehicle detected by the outside-vehicleinformation detecting unit 12030.

The sound/image output section 12052 transmits an output signal of atleast one of a sound and an image to an output device capable ofvisually or auditorily notifying information to an occupant of thevehicle or the outside of the vehicle. In the example of FIG. 13, anaudio speaker 12061, a display section 12062, and an instrument panel12063 are illustrated as the output device. The display section 12062may, for example, include at least one of an on-board display and ahead-up display.

FIG. 14 is a diagram depicting an example of the installation positionof the imaging section 12031.

In FIG. 14, the imaging section 12031 includes imaging sections 12101,12102, 12103, 12104, and 12105.

The imaging sections 12101, 12102, 12103, 12104, and 12105 are, forexample, disposed at positions on a front nose, sideview mirrors, a rearbumper, and a back door of the vehicle 12100 as well as a position on anupper portion of a windshield within the interior of the vehicle. Theimaging section 12101 provided to the front nose and the imaging section12105 provided to the upper portion of the windshield within theinterior of the vehicle obtain mainly an image of the front of thevehicle 12100. The imaging sections 12102 and 12103 provided to thesideview mirrors obtain mainly an image of the sides of the vehicle12100. The imaging section 12104 provided to the rear bumper or the backdoor obtains mainly an image of the rear of the vehicle 12100. Theimaging section 12105 provided to the upper portion of the windshieldwithin the interior of the vehicle is used mainly to detect a precedingvehicle, a pedestrian, an obstacle, a signal, a traffic sign, a lane, orthe like.

Incidentally, FIG. 14 depicts an example of photographing ranges of theimaging sections 12101 to 12104. An imaging range 12111 represents theimaging range of the imaging section 12101 provided to the front nose.Imaging ranges 12112 and 12113 respectively represent the imaging rangesof the imaging sections 12102 and 12103 provided to the sideviewmirrors. An imaging range 12114 represents the imaging range of theimaging section 12104 provided to the rear bumper or the back door. Abird's-eye image of the vehicle 12100 as viewed from above is obtainedby superimposing image data imaged by the imaging sections 12101 to12104, for example.

At least one of the imaging sections 12101 to 12104 may have a functionof obtaining distance information. For example, at least one of theimaging sections 12101 to 12104 may be a stereo camera constituted of aplurality of imaging elements, or may be an imaging element havingpixels for phase difference detection.

For example, the microcomputer 12051 can determine a distance to eachthree-dimensional object within the imaging ranges 12111 to 12114 and atemporal change in the distance (relative speed with respect to thevehicle 12100) on the basis of the distance information obtained fromthe imaging sections 12101 to 12104, and thereby extract, as a precedingvehicle, a nearest three-dimensional object in particular that ispresent on a traveling path of the vehicle 12100 and which travels insubstantially the same direction as the vehicle 12100 at a predeterminedspeed (for example, equal to or more than 0 km/hour). Further, themicrocomputer 12051 can set a following distance to be maintained infront of a preceding vehicle in advance, and perform automatic brakecontrol (including following stop control), automatic accelerationcontrol (including following start control), or the like. It is thuspossible to perform cooperative control intended for automatic drivingthat makes the vehicle travel autonomously without depending on theoperation of the driver or the like.

For example, the microcomputer 12051 can classify three-dimensionalobject data on three-dimensional objects into three-dimensional objectdata of a two-wheeled vehicle, a standard-sized vehicle, a large-sizedvehicle, a pedestrian, a utility pole, and other three-dimensionalobjects on the basis of the distance information obtained from theimaging sections 12101 to 12104, extract the classifiedthree-dimensional object data, and use the extracted three-dimensionalobject data for automatic avoidance of an obstacle. For example, themicrocomputer 12051 identifies obstacles around the vehicle 12100 asobstacles that the driver of the vehicle 12100 can recognize visuallyand obstacles that are difficult for the driver of the vehicle 12100 torecognize visually. Then, the microcomputer 12051 determines a collisionrisk indicating a risk of collision with each obstacle. In a situationin which the collision risk is equal to or higher than a set value andthere is thus a possibility of collision, the microcomputer 12051outputs a warning to the driver via the audio speaker 12061 or thedisplay section 12062, and performs forced deceleration or avoidancesteering via the driving system control unit 12010. The microcomputer12051 can thereby assist in driving to avoid collision.

At least one of the imaging sections 12101 to 12104 may be an infraredcamera that detects infrared rays. The microcomputer 12051 can, forexample, recognize a pedestrian by determining whether or not there is apedestrian in imaged images of the imaging sections 12101 to 12104. Suchrecognition of a pedestrian is, for example, performed by a procedure ofextracting characteristic points in the imaged images of the imagingsections 12101 to 12104 as infrared cameras and a procedure ofdetermining whether or not it is the pedestrian by performing patternmatching processing on a series of characteristic points representingthe contour of the object. When the microcomputer 12051 determines thatthere is a pedestrian in the imaged images of the imaging sections 12101to 12104, and thus recognizes the pedestrian, the sound/image outputsection 12052 controls the display section 12062 so that a squarecontour line for emphasis is displayed so as to be superimposed on therecognized pedestrian. The sound/image output section 12052 may alsocontrol the display section 12062 so that an icon or the likerepresenting the pedestrian is displayed at a desired position.

4. Working Examples

Next, working examples of the present disclosure are described.

(Evaluation of Electric Characteristic)

First, after a Si substrate with an ITO electrode (lower electrode)having a thickness of 50 nm was cleaned in a UV/ozone process, anorganic photoelectric conversion layer was deposited at a substratetemperature of 40° C. in a resistance heating method while rotating asubstrate holder in vacuum of 1×10⁻⁵ Pa or less. For a material of theorganic photoelectric conversion layer, 3, 6BP-BBTN in Expression (1)below was used as a hole transporting material (P material), asubphthalocyanine derivative (F₆-SubPc-OPh₂₆F₂) was used as a lightabsorber, and fullerene C60 was used as an electron transportingmaterial (N material), which were concurrently deposited. A ratio of adeposition speed was 3, 6BP-BBTN:F₆-SubPc-OPh₂₆F₂: C60=4:4:2. Filmformation was so performed that the total film thickness was 230 nm.Subsequently, B4PyPMP was deposited with a thickness of 5 nm in a vacuumdeposition method at a substrate temperature of 0° C. as a buffer layeron the photoelectric conversion layer. Next, as the upper electrode 17,a film of ITO was formed by sputtering to have a thickness of 100 nm,and then subjected to heating treatment at 160° C. Thereby, aphotoelectric conversion element (Experiment Example 1) having aphotoelectric conversion region of 1 mm×1 mm was fabricated.

Additionally, photoelectric conversion elements serving as ExperimentExamples 2 to 8 were fabricated. In Experiment Examples 2 and 3,photoelectric conversion elements were fabricated by using a methodsimilar to that of Experiment Example 1 except that the organicphotoelectric conversion layers were formed at substrate temperatures of25° C. (Experiment Example 2) and 0° C. (Experiment Example 3). InExperiment Example 4, a photoelectric conversion element was fabricatedby using a method similar to that of Experiment Example 3 except thatheating treatment was omitted (As depo) after the organic film wasformed (after the buffer layer was formed). In Experiment Example 5, aphotoelectric conversion element was fabricated by using a methodsimilar to that of Experiment Example 3 except that BP-ChDT (Expression(2)) was used as a P material. In Experiment Examples 6, 7, and 8,photoelectric conversion elements were fabricated by using DBPA(Expression (3)) as P materials and setting −10° C. and ANL 160° C.(Experiment Example 6), −10° C. and As depo (Experiment Example 7), and40° C. and ANL 160° C. (Experiment Example 8) as the respectivesubstrate temperatures when the organic photoelectric conversion layerswere formed and the respective heating treatment conditions after theorganic films were formed.

The responsiveness (afterimage characteristics) of Experiment Examples 1to 8 were evaluated. The afterimage characteristics were evaluated bymeasuring a rate at which the bright current value observed at the timeof light irradiation fell after the light irradiation was stopped usingthe semiconductor parameter analyzer. Specifically, the amount of lightwith which the photoelectric conversion element was irradiated from thelight source via the filter was set at 1.62 W/cm₂, and the bias voltageto be applied between the electrodes was set at −2.6 V. After a steadycurrent was observed in this state, the light irradiation was stoppedand the current was observed to decay. Thereafter, with the areasurrounded by a current-time curve and the dark current set as 100%, thetime elapsed before the area becomes 3% was considered as an index ofthe responsiveness. All the evaluations were performed at a roomtemperature.

In addition, the quantum efficiency (external quantum efficiency; EQE)of Experiment Examples 1 to 8 was evaluated by using a semiconductorparameter analyzer. Specifically, the external photoelectric conversionefficiency was calculated from a bright current value and a dark currentvalue in a case where the amount of light (LED light having a wavelengthof 560 nm) with which the photoelectric conversion element is irradiatedfrom the light source via the filter was set at 1.62 μW/cm² and the biasvoltage to be applied between the electrodes was set to −2.6 V.

(Transmission Electron Microscope (TEM) Analysis)

In addition, TEM observation samples of the cross sections of theorganic photoelectric conversion layers corresponding to ExperimentExamples 1 to 8 were fabricated, and the P material domains in theorganic photoelectric conversion layers were observed. The domains ofthe P materials (organic semiconductor materials each having the holetransporting property) were confirmed by observing transmission imageswith a transmission electron microscope.

First, a thin sample was fabricated from the region of the organicphotoelectric conversion layer of the sample of Experiment Example 1above by using a focused ion beam (Focused Ion Beam; FIB, HELIOS NANOLAB400S manufactured by FEI), and then a damaged layer of an FIB-processedend surface was removed by an ion milling machine (Model 1040manufactured by Fischione). TEM (JEM-300F manufactured by JEOL) observeda transmission image at an accelerating voltage of 300 kV in the stateof low irradiation electron beams. The transmission image was observedwith the transmission image out of focus, that is, deviated byapproximately 1500 nm from the just focus position onto the underside asa defocus condition for observing a domain. Additionally, similarmethods were used to perform the transmission microscope analyses ofExperiment Examples 2 to 8 above.

Film formation Electric characteristic Interference fringe SubstrateHeating Afterimage Number temperature treatment characteristic

Length Angle of P material (° C.) condition ( 

 ) (%) ( 

 ) (°) lines Experiment Example 1 3, 6BP-BBTN 40 ANL 160° C. 1.3 80.4117.9 87.1 4 Experiment Example 2 3, 6BP-BBTN 28 ANL 

3.5 79.8 61.4 86.6 2 Experiment Example 3 3, 6BP-BBTN 0 ANL 160° C. 7.862.3 31.6 49.7 2 Experiment Example 4 3, 6BP-BBTN 0

— 61.8 — — — Experiment Example 5 BP-ChDT 0 ANL  

0.16 85.1 90.0 83.1 2 Experiment Example 6 DBPA −10 ANL 

— — 101.2 82.1 3 Experiment Example 7 DBPA −10 ANL 

4.4 — 45.8 63.7 2 Experiment Example 8 DBPA 40 ANL 180° C. >1000Considerably 107.7 71.9 10 degraded

indicates data missing or illegible when filed

FIG. 15 includes a TEM image (A) in which an interference fringe portionof Experiment Example 1 is enlarged, and (B) obtained by measuring thesignal intensity of the TEM image by TEM image software (DigitalMicrograph). The interference fringe of the TEM image appears as a peakof high points or low points of the signal intensity in accordance withthe strength of contrast thereof. As described above, paired adjacentlines included in interference fringe represent the molecular period ofthe P material in the major axis direction. While the P material used inExperiment Example 1 had a molecular length of approximately 3 nm,paired lines included in the interference fringe in FIG. 15(B) had aninterval of 2.2 nm. This allows the interference fringe to beparaphrased with an interference fringe having the period of the Pmaterial in the major axis direction.

FIG. 16 illustrates respective TEM images of Experiment Example 1 (A)and Experiment Example 4 (B). FIG. 17 illustrates respective TEM imagesof Experiment Example 6 (A) and Experiment Example 8 (B). Table 1tabulates the P materials used in Experiment Examples 1 to 8, theconditions for forming the organic photoelectric conversion layers, andthe respective electric characteristics and transmission microscopeanalysis results. In Experiment Examples 1 and 4 in which 3, 6BP-BBTNwas used as P materials. In Experiment Example 1 in which heatingtreatment was performed at 160° C. after an organic film was formed, aninterference fringe was observed that indicated a domain extending inthe film-thickness direction (e.g., in the circle in FIG. 16(A)). InExperiment Example 4 in which no heating treatment was performed (Asdepo) after an organic film was formed, no interference fringe wasobserved. Experiment Example 1 offered a more improved afterimagecharacteristic than Experiment Example 4, and further offered increasedquantum efficiency. This made clear the effectiveness of a domain in anorganic photoelectric conversion layer. In addition, in ExperimentExample 3 in which BP-ChDT was used as a P material, and an excellentafterimage characteristic and quantum efficiency were offered, a domainwas also confirmed that extends in the film-thickness direction. Thisindicated that the formation of a domain extending in the film-thicknessdirection was significant for improvement in an electric characteristic.

In contrast, in Experiment Example 6 in which DBPA was used as a Pmaterial, and an organic photoelectric conversion layer was formed at40° C., a domain was certainly confirmed in the organic photoelectricconversion layer, but an afterimage characteristic and quantumefficiency were both considerably degraded. In Experiment Example 8, alarge number (ten or more) of interference fringes were confirmed. Thisindicated that too large a domain caused an electric characteristic tobe degraded.

It is to be noted that it has been described in the above-describedembodiment that the angle formed between an interference fringe and theelectrode surface of the lower electrode 15 is preferably more than 450and 900 or less, and the reason for this is as follows. In a case wherea domain is formed in an organic photoelectric conversion layer, thisdomain serves as a charge transporting path. To more efficientlytransport holes or electrons in the directions of the upper and lowerelectrodes, it is desirable to configure a domain extending vertical tothe electrode surface. For example, a domain including a P materialcontributes to the transporting efficiency of holes, and this increasesthe response speed to offer a favorable afterimage characteristic. Arelatively favorable afterimage characteristic is obtained in thepresent working example even if the angle formed between an interferencefringe and the electrode surface is 49.7° (Experiment Example 3). Asdescribed above, it is preferable that the angle formed between aninterference fringe and the electrode surface be more than 450 and lessthan 900 as the extending direction of the interference fringe. Inaddition, an angle of 630 or more and 900 or less is more preferable,and an angle of 820 or more and 900 or less is still more preferable.

In addition, it has been described in the above-described embodimentthat the interval between two adjacent lines included in an interferencefringe preferably falls within ±50% of the molecular length of a p-typesemiconductor, and the reason for this is as follows. While themolecular length of the 3, 6BP-BBTN used in Experiment Example 1 in themajor axis direction is approximately 3 nm, the interval of theinterference fringe is 2.2 nm, resulting in a difference ofapproximately 27%. A major factor in this difference is a molecularlength axis that is not vertical to the extending direction of theinterference fringe or the direction for transmitting electrons, butinclined. In a case where the molecular length axis is inclined withrespect to the electrode surface, the interval between paired linesincluded in the interference fringe is shorter than the molecularlength. Further, the possible variable factors caused by the focusamount of a transmission electron microscope are as follows. As a firstfactor, an image of the transmission electron microscope is blurred indifferent ways in accordance with a defocus amount, and a larger defocusamount prolongs the interval between paired lines included in theinterference fringe. As a second factor, the defocus amount varies inaccordance with an error of a position with no defocus. As a benchmark,a defocus amount of 0 is determined from the position of the weakestcontrast by visually confirming the contrast of an end of a sample whilechanging the height of the sample. As a third factor, a focus amountdepends on the position of a p-type semiconductor in a sample, therebyvarying the interval between paired lines. As described above, it ispreferable that the interval between two adjacent lines included in aninterference fringe fall within ±50% of the molecular length of thep-type semiconductor.

Description has been given above by referring to the embodiment, themodification example, and the working examples, but the content of thepresent disclosure is not limited to the above-described embodiment andthe like, and various modifications are possible. For example, in theabove-described embodiment, the photoelectric conversion element has aconfiguration in which the organic photoelectric conversion section 11Gthat detects green light, and the inorganic photoelectric conversionsection 11B and the inorganic photoelectric conversion section 11R thatdetect blue light and red light, respectively, are stacked. However, thecontent of the present disclosure is not limited to such a structure.That is, the organic photoelectric conversion section may detect the redlight or the blue light, or the inorganic photoelectric conversionsections may detect the green light.

In addition, the number of these organic photoelectric conversionsections and inorganic photoelectric conversion sections or a proportionthereof are not limited. The two or more organic photoelectricconversion sections may be provided or color signals of a plurality ofcolors may be obtained with the organic photoelectric conversion sectionalone. Further, a structure is not limited to the structure in which theorganic photoelectric conversion section and the inorganic photoelectricconversion sections are stacked in the vertical direction, but theorganic photoelectric conversion section and the inorganic photoelectricconversion sections may be placed side by side along a substratesurface.

Moreover, the above-described embodiment or the like exemplifies theconfiguration of the backside illumination type solid-state imagingdevice, but the content of the present disclosure is also applicable toa solid-state imaging device of a front surface illumination type. Inaddition, the photoelectric conversion element of the present disclosuredoes not necessarily have to include all of the components described inthe embodiment above, and may include another layer, conversely.

It is to be noted that the effects described herein are merely examples,but not limitative. In addition, there may be other effects.

It is to be noted that the present disclosure may have the followingconfigurations.

(1)

A photoelectric conversion element including:

a first electrode;

a second electrode disposed to be opposed to the first electrode; and

an organic photoelectric conversion layer provided between the firstelectrode and the second electrode, the organic photoelectric conversionlayer having a domain of one organic semiconductor material therein,

the domain of the one organic semiconductor material having apercolation structure in which the domain vertically extends in theorganic photoelectric conversion layer in a film-thickness direction,and having a smaller domain length in a plane direction of the organicphotoelectric conversion layer than a domain length in thefilm-thickness direction of the organic photoelectric conversion layer.

(2)

The photoelectric conversion element according to (1), in which

the organic photoelectric conversion layer has an interference fringe ina cross-sectional photograph in the film-thickness direction, thecross-sectional photograph being taken by a transmission electronmicroscope under a defocus condition, the interference fringe includingtwo or more lines, and

an interval between the two or more lines included in the interferencefringe falls within ±50% of a molecular length of the one organicsemiconductor material.

(3)

The photoelectric conversion element according to (2), in which theinterference fringe has a length of 20 nm or more.

(4)

The photoelectric conversion element according to (2) or (3), in whichan angle formed between the interference fringe and an electrode surfaceof the first electrode is more than 450 and 90° or less.

(5)

The photoelectric conversion element according to any of (2) to (4), inwhich the interference fringe includes less than ten lines.

(6)

The photoelectric conversion element according to any of (1) to (5), inwhich an interface between the organic photoelectric conversion layerand the second electrode has a surface roughness of 10 nm or less.

(7)

The photoelectric conversion element according to any of (1) to (6), inwhich the one organic semiconductor material has a hole transportingproperty.

(8)

A solid-state imaging device including

pixels each including one or more organic photoelectric conversionsections,

the organic photoelectric conversion sections each include

-   -   a first electrode,    -   a second electrode disposed to be opposed to the first        electrode, and    -   an organic photoelectric conversion layer provided between the        first electrode and the second electrode, the organic        photoelectric conversion layer having a domain of one organic        semiconductor material therein,    -   the domain of the one organic semiconductor material having a        percolation structure in which the domain vertically extends in        the organic photoelectric conversion layer in a film-thickness        direction, and having a smaller domain length in a plane        direction of the organic photoelectric conversion layer than a        domain length in the film-thickness direction of the organic        photoelectric conversion layer.        (9)

The solid-state imaging device according to (8), in which the one ormore organic photoelectric conversion sections and one or more inorganicphotoelectric conversion sections are stacked in each pixel, the one ormore inorganic photoelectric conversion sections each performingphotoelectric conversion in a wavelength region different fromwavelength regions of the organic photoelectric conversion sections.

(10)

The solid-state imaging device according to (9), in which

the inorganic photoelectric conversion sections are each embedded andformed in a semiconductor substrate, and

the organic photoelectric conversion sections are each formed on a firstsurface side of the semiconductor substrate.

(11)

The solid-state imaging device according to (10), in which a multilayerwiring layer is formed on a second surface side of the semiconductorsubstrate.

(12)

The solid-state imaging device according to (10) or (11), in which

the organic photoelectric conversion sections each photoelectricallyconvert green light, and

an inorganic photoelectric conversion section that photoelectricallyconverts blue light and an inorganic photoelectric conversion sectionthat photoelectrically converts red light are stacked in thesemiconductor substrate.

(13)

The solid-state imaging device according to any of (8) to (12), in whicha plurality of the organic photoelectric conversion sections is stackedin each pixel, the plurality of the organic photoelectric conversionsections performing photoelectric conversion in respective wavelengthregions different from each other.

This application claims the priority on the basis of Japanese PatentApplication No. 2017-222977 filed with Japan Patent Office on Nov. 20,2017, the entire contents of which are incorporated in this applicationby reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations, and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

1. A photoelectric conversion element, comprising: a first electrode; asecond electrode disposed to be opposed to the first electrode; and anorganic photoelectric conversion layer provided between the firstelectrode and the second electrode, the organic photoelectric conversionlayer having a domain of one organic semiconductor material therein, thedomain of the one organic semiconductor material having a smaller domainlength in a plane direction of the organic photoelectric conversionlayer than a domain length in a film-thickness direction of the organicphotoelectric conversion layer, and the one organic semiconductormaterial has a hole transporting property.
 2. The photoelectricconversion element according to claim 1, wherein the organicphotoelectric conversion layer has an interference fringe in across-sectional photograph in the film-thickness direction, thecross-sectional photograph being taken by a transmission electronmicroscope under a defocus condition, the interference fringe includingtwo or more lines, and an interval between the two or more linesincluded in the interference fringe falls within ±50% of a molecularlength of the one organic semiconductor material.
 3. The photoelectricconversion element according to claim 2, wherein the interference fringehas a length of 20 nm or more.
 4. The photoelectric conversion elementaccording to claim 2, wherein an angle formed between the interferencefringe and an electrode surface of the first electrode is more than 450and 90° or less.
 5. The photoelectric conversion element according toclaim 2, wherein the interference fringe includes less than ten lines.6. The photoelectric conversion element according to claim 1, wherein aninterface between the organic photoelectric conversion layer and thesecond electrode has a surface roughness of 10 nm or less.
 7. Asolid-state imaging device, comprising: pixels each including one ormore organic photoelectric conversion sections, the organicphotoelectric conversion sections each include a first electrode, asecond electrode disposed to be opposed to the first electrode, and anorganic photoelectric conversion layer provided between the firstelectrode and the second electrode, the organic photoelectric conversionlayer having a domain of one organic semiconductor material therein, thedomain of the one organic semiconductor material having a smaller domainlength in a plane direction of the organic photoelectric conversionlayer than a domain length in a film-thickness direction of the organicphotoelectric conversion layer, and the one organic semiconductormaterial has a hole transporting property.
 8. The solid-state imagingdevice according to claim 7, wherein the one or more organicphotoelectric conversion sections and one or more inorganicphotoelectric conversion sections are stacked in each pixel, the one ormore inorganic photoelectric conversion sections each performingphotoelectric conversion in a wavelength region different fromwavelength regions of the organic photoelectric conversion sections. 9.The solid-state imaging device according to claim 8, wherein theinorganic photoelectric conversion sections are each embedded and formedin a semiconductor substrate, and the organic photoelectric conversionsections are each formed on a first surface side of the semiconductorsubstrate.
 10. The solid-state imaging device according to claim 9,wherein a multilayer wiring layer is formed on a second surface side ofthe semiconductor substrate.
 11. The solid-state imaging deviceaccording to claim 9, wherein the organic photoelectric conversionsections each photoelectrically convert green light, and an inorganicphotoelectric conversion section that photoelectrically converts bluelight and an inorganic photoelectric conversion section thatphotoelectrically converts red light are stacked in the semiconductorsubstrate.
 12. The solid-state imaging device according to claim 7,wherein a plurality of the organic photoelectric conversion sections isstacked in each pixel, the plurality of the organic photoelectricconversion sections performing photoelectric conversion in respectivewavelength regions different from each other.
 13. The solid-stateimaging device according to claim 7, wherein the domain of the oneorganic semiconductor material has a percolation structure in which thedomain vertically extends in the organic photoelectric conversion layerin the film-thickness direction.